In the first episode, a father and daughter find themselves treading water for almost an hour, hundreds of metres out at sea, after being swept out by a rip current. In Kinsale, Ireland, three fishermen swim for their lives as their trawler is smashed on to rocks. And in London, an unlucky tourist is minutes from hypothermia after his attempt to take a selfie lands him in the Thames.

Off the coast of Bridlington, a kayaker has been missing for an hour, and only the crews' expert coastal knowledge can help track him down. A crew member on his first shout races to a dinghy capsize to find a man losing consciousness in the water. And when a fishing trawler sinks off the coast of the Shetland Islands, the fishermen and RNLI crew aboard must swim for their lives.

In Ireland, the Castletownbere crew race to rescue a lone yachtsman who has lost his mast and is drifting powerless in 10-metre waves, 45 miles out to sea. In Minehead a woman on a clifftop walk has gone missing, and after 17 hours the crew are called to search the shoreline. And for an injured horse rider on a remote beach, the Porthcawl crew are the only way to emergency medical help.

In Bangor, Northern Ireland, crews are tasked to find two teenage paddle boarders, blown offshore towards nearby shipping lanes. The Tenby crew in West Wales must race to a dog who's fallen over a cliff - before worried members of the public attempt to rescue it themselves. And on the North Norfolk coast, the harrowing hovercraft rescue of three young sisters still brings back painful memories for the Hunstanton crew.

Every day around the UK, an army of unpaid volunteers put their lives on the line to try and save complete strangers. Saving Lives at Sea tells the story of the ordinary men and women of the Royal National Lifeboat Institution (RNLI) who, across the country, are ready to launch their boats and race to the rescue within minutes of a cry for help - 24 hours a day, 365 days a year, whatever the weather. Using footage shot on crews' own cameras, this series takes us right into the heart of the action, capturing the unpredictable work of the RNLI in never-before-seen detail. In south west Wales, the Tenby crew race to a kayaker with suspected back and neck injuries after being caught out by a freak wave. Neighbouring Cornish crews must join forces in an epic 11-hour battle to stop a 3,600-tonne coaster breaking up on the rocks. And the Dart and Salcombe crews are astonished to be paged to the biggest shout of their lives.

In episode six of this 12-part series, on one of the hottest days of the year, the Dover crew race to a Channel Swimmer who's collapsed within sight of the French coast. In Mudeford, there are growing fears for a dinghy sailor who is four miles out in rough seas and refusing to accept help, and the Tenby crew are called to a runaway yacht just metres from running aground.

When a climber falls in a remote cave on the Gower Peninsula, the Mumbles crew are called in to search and rescue. In Portreath, lifeguards battle to save a teenager who is determined to surf despite red flag warnings. And on the Isle of Wight, the Yarmouth crew must locate a man in the water amongst over a thousand boats competing in the Round the Island Race.

In Ilfracombe, a father and son find themselves in danger after jumping in to rescue a drowning dog. The Minehead crew must scour the cliffs and shoreline after a young woman goes missing in a distressed state. And when they're paged to a man seen entering the Thames, the Tower crew face the possibility they may not find him in time.

The Aberystwyth crew must improvise when a local paraglider crash-lands at the bottom of steep cliffs. When an adventurous seal is discovered on the steps of a block of flats, Redcar's newest recruit is first on the scene. And in Minehead, a challenging rescue forces an inexperienced crew member to consider her future.

As the summer sun comes out, so do the fun seekers, and crews around the country get ready for action. In Southend, a family of five out sightseeing are a mile off shore and waist-deep in water after being caught out by the tide. The Shoreham crew are paged in the early hours after a drunken festival-goer jumps in the river. And the Brighton crew fear the worst when a man tombstones off the pier at low tide.

When an early morning dog walker spots a flare off shore, the Rhyl crew race to one of the most mysterious shouts they have seen. The Lowestoft crew find themselves paged to help to a sailor who doesn't want to be rescued. And at Tower, a good samaritan is clinging on for his life after trying to rescue a dog which has jumped into the Thames.

In Tenby, police searching for a boat thief call for lifeboat assistance. The Mumbles lifeguards and lifeboat crew race to help two kayakers adrift in a boat laden with beer. And when two yachts capsize off Portsmouth, the crew must make fast decisions about who to rescue first.

Out at sea, minutes and even seconds can make the difference between life and death. On the south coast of Devon, the crew of Salcombe lifeboat station are called to two of the highest level of emergencies at sea - a mayday call to a fisherman pulled to the bottom of the sea ensnared in his own fishing gear and a devastating fire on a boat 15 miles out in the Channel. Over 200 miles away in the waters off Anglesey, as they go to the rescue of a father and his 13-year-old son missing at sea, the crew of Moelfre station uncover a story of survival and heroism.

From first timers at sea to salty old skippers, the wrong conditions can catch anyone off their guard leaving them in need of rescuing. On the east coast of Ireland, the crew of Courtown's inshore lifeboat face one of their most challenging shouts ever - in deep water they must keep a teenage girl with suspected spinal injuries immobile and afloat for 40 minutes, knowing any movement could leave her paralysed for life. Meanwhile on the English Riviera in Devon, the Torbay crew have just minutes to find a capsized kayaker before she is dashed against the rocks, and in Dartmouth, an 81-year-old sailor, fallen overboard in the middle of the night, is left clinging to a rope for his life.

Keeping watch over the River Thames, the crew at Tower in central London, the busiest of the RNLI's 238 stations, are called to a man reported in the water eight miles downstream. On arrival, they discover a river bus already on the scene and their crew desperately trying to hang on to the unmoving man before he disappears under the water. At one of the most remote stations, Trearddur Bay on Anglesey, the crew are called to an inaccessible coastal fishing spot, where an angler has plunged face first down a cliff onto rocks. With no helicopter available, the crew and their small inshore lifeboat are the only option to get him to urgent medical treatment. While in Portsmouth, gale force winds and a churning sea make a routine rescue particularly challenging.

In Brighton the crew are called out to what they think is just a routine job - towing a yacht that has lost power back to harbour - but a sudden spring squall and mountainous waves leave the crew fighting to save the yacht and themselves from being dashed on the shore. Off the east coast of Ireland, the crew of the small fishing village of Howth respond to an emergency call from a family on a local beach - a teenage girl out on a sailing dinghy has capsized and is now being swept out into the Irish Sea. While on the island of Anglesey, the crew of Moelfre are also heading out to help a family in trouble - two women have swum out to save a friend's young son being blown out to sea on an inflatable, but it quickly becomes the rescuers that need saving themselves

In Torbay in Devon the seas are often crowded with sailing craft of all shapes and sizes – when two collide the Torbay lifeboat crew are called out to provide emergency medical assistance for a potentially life-changing injury. On the south coast of Wales, the Porthcawl crew have just seconds to spare when two teenagers on holiday get caught on a rocky outcrop by a large swell and a rising spring tide. While in Yorkshire, the Flamborough crew have to pluck a man from danger after he jumps off a hundred-foot cliff for a dare.

There are many reasons why the thousands of yellow-wellied volunteers first joined up, but they all share a common desire to help those in trouble. At Anstruther station in Scotland, one of their newest helms, George, takes charge for his first shout to a serious medical evacuation. A woman has slipped on one of the most notorious parts of the station's patch, the Chain Walk, where walkers have to negotiate steep cliffs while hanging on to chains hammered into the rock. On the north coast of Devon, the crew at Appledore station make a life-or-death dash to rescue two teenagers caught in a cave being flooded by the tide and pounded by waves, but arriving at the scene they discover that saving the young couple will mean putting themselves in danger. And when Storm Henry hits the British Isles and has shipping running for safe harbours, a cargo ship loses all power and is left at the mercy of the waves and 90-mile-an-hour winds. As she drifts inexorably towards the rugged cliffs of north Devon, two lifeboats are launched but even with their combined power they face a losing battle trying to tow the huge ship out of harm's way

On the north coast of Kent, new crew member Ruth is on board for one of her first ever shouts. Off the Essex coast, the crew of West Mersea station launch to reports of a life raft in the North Sea. 10 miles along the coast at Clacton the crew get a call in the middle of the night to look for two people in the sea.

For the thousands of volunteers who guard our seas and waterways, saving other people can mean making sacrifices in their own lives. Volunteer and doctor Adam makes a 500-mile round trip every time he puts in a shift at Tower Lifeboat Station in the heart of London, but his medical skills prove invaluable when the crew are called to help the police try and save a man who is stuck under a pier on the Thames with the tide rising. In north Wales, when police officer Vinny isn't patrolling the streets of Rhyl, he volunteers for the lifeboat crew. When the pagers go off one summer evening, Vinny finds himself heading out into the darkness to try and rescue two teenage boys who have chased a wayward football into the sea and get caught in a treacherous current. While across the Irish Sea in Dunmore East, the lifeboat crew's evening is interrupted by an urgent call to a motor boat stranded several miles out and taking on water.

As storm Ophelia hits the British Isles, on the south east coast of Ireland the pagers of the Rosslare crew go off - a small yacht with three people on board is caught in one of the worst storms in living memory. In Devon, the crew at Appledore race an incoming tide to try and reach a man stuck fast in quicksand, while on the north coast of Cornwall the crew of St Agnes must battle through huge breaking waves to reach two young boys being swept out to sea in a deadly rip current.

Off the packed beach at Blackpool, the crew race after a teenage girl being swept out to sea on an inflatable dinghy. While on the miles of long sandy beaches at Rhyl in north Wales, amongst the holidaying crowds two girls get caught in a deadly current while swimming just a few metres from shore. And on the Cornish coast a woman, trying out the extreme sport of coasteering for the very first time, falls several metres down a cliff face onto a beach with a fast incoming tide.

The volunteers of the RNLI race to the scene of a plane crash on a busy beach, search for a man missing at sea in the Channel Islands and battle to save a horse from drowning.

The volunteers of the RNLI race to save a fisherman from a burning boat, a man stuck in freezing mud, and a walker who, after trying to rescue her dog, now needs saving herself.

The volunteers of the RNLI race to save three kids caught in a cave by the rising tide, a yacht caught in a storm, and search for a pensioner missing for several hours.

The RNLI volunteers race to the rescue of a rock climber who has fallen over 40 feet, a paraglider who has crashed into the sea and a man drifting offshore in a toy dinghy.

The RNLI volunteers race to the rescue of a diver found unconscious 30 metres underwater, a yacht sinking in the middle of the Channel and a windsurfer caught out in a storm.

RNLI volunteers race to the rescue of two five-year-old girls blown out to sea on an inflatable and a mother and daughter trapped by the tide, while one crew member saves his own dad.

The RNLI volunteers race to the rescue of the last inhabitant of a remote island, a kayaker in trouble in the North Sea and, on the river Thames, a dog trapped by the tide.

The RNLI volunteers race to the rescue of a huge cargo ship aground on a sandbank, a kayaker who has set off an emergency beacon, and a horse in danger of drowning in a river.

RNLI volunteers race to the rescue of a shark attack victim, two boys being swept out to sea in a rip current and two fisherman caught by the tide and now stranded in a rising sea.

RNLI volunteers teams come to the aid of two teenagers stuck in mud on the Humber estuary and a boat that has lost its mast on the freezing waters of Loch Ness.

The volunteers of the RNLI race to save two paddleboarders being swept into a shipping lane, search for a missing fisherman and abandon a crewmate’s wedding when the pager calls.

The volunteers of the RNLI race to rescue a stranded porpoise, a teenager trapped by the tide on a rocky outcrop and the crew of a fishing boat on fire.

The volunteers of the RNLI race to rescue a paddleboarder being blown out to sea, a man overboard and two teenage girls trapped on a sandbank and at risk of drowning.

The volunteers of the RNLI race to save a sinking schooner and a walker with a broken leg, while cries for help in the early hours of the morning lead to an eerie night-time search.

The volunteers of the RNLI race to save a stricken fishing boat in a force-eight gale, a yacht trapped on a weir in Loch Ness and a puppy that has swallowed a fishing hook.

The RNLI volunteers race against time to try and save three people in the water in the Bristol Channel, a father and son trapped against a cliff face and a badly injured sailor.

The volunteers of the RNLI race to save a family trapped in their car, slowly being engulfed by the sea, two kayakers close to drowning, and a fossil hunter cut off by the tide.

The RNLI volunteers face a search in one of the worst storms in living memory, race to save three people caught in a rip current and two men stuck on an oil rig's anchor chain.

The RNLI volunteers search for a missing kitesurfer, race to rescue a father and daughter being swept out to sea and try to save all nine lives of a casualty in the Thames.

The RNLI volunteers race to save a teenage paddleboarder being swept out to sea, a sinking cargo ship and a yacht being battered by an Atlantic storm.

In Porthcawl, the volunteers of the RNLI race to save a surfer at the mercy of Storm Brendan. Meanwhile, in Selsey, a family's day out for a spot of paddleboarding goes badly awry when the father becomes separated from his young children, leaving them stranded on a rapidly dwindling sandbank.

The volunteers of the RNLI battle to save a mother and her son who are caught in a rip current, plus a man who has fallen over 100 feet from the top of a cliff.

The lifeboat volunteers pluck a fallen climber out of the sea in Wales and is within seconds of falling unconscious. Meanwhile in Scotland, a team rescue a 170-ton fishing boat that is perilously close to the rocks in gale force winds, and in Minehead, three kayakers are swept out to sea as darkness falls.

The crew at Tower, on the River Thames in London, is the busiest of all the lifeboat stations, averaging more than 500 shouts a year and aiming to launch to any emergency in under 90 seconds. When a call comes in about a man in the water near the Thames Barrier, they reach him with just moments to spare. In Fleetwood, on the Lancashire coast, a desperate 999 call alerts the crew to a bait digger - out looking for worms on the sand flats - who has been caught out by the incoming spring tide and is in danger of being submerged and swept out to sea.

In Trearddur Bay, the RNLI crew battle through gale force winds and huge waves as they try to save a surfer, as their worried families watch on from the shore. On the same stretch of Welsh coast, the Llandudno and Rhyl lifeboats are involved in a desperate search for a fishing vessel that's reported missing.

In St Agnes, the crew is involved in a race against time to rescue two young men. They are reported to be struggling in the water near a notorious headland known as Tubby's Head. In Whitby, North Yorkshire, Leah is training to be the station's first female helm, and her skills are put to the test when she is called out to rescue a walker who's fallen and injured her leg on inaccessible rocks by the seal colony at Ravenscar.

Whenever the crew’s pager sounds, they know they must prepare for all eventualities. At Beachy Head, the Eastbourne crew have to deal with a base jumper’s disastrous takeoff. Just along the Sussex coast in Newhaven, a man faces a race against time as he suffers a seizure on board a tall ship. At Loch Ness, a World War II sea plane runs into mechanical trouble. And in Rhyl, a dog chasing seagulls into the sea bites off more than she can chew.

On Ireland's south-east coast, the three RNLI crews at Dunmore East, Kilmore Quay and Rosslare battle to save a cargo ship that has lost all power and is drifting towards rocks. In Hoylake, on the Wirral, a vast multi-agency effort is required to rescue a mother and daughter who have got stuck in the mud and, 65 miles to the west, in the coastal village of Porthdinllaen, the crew respond to a mayday call from a yacht five miles out in the Irish Sea that is requesting an immediate medical evacuation.

Just off the west coast of Scotland, on the rugged Isle of Mull, the Tobermory lifeboat crew have to battle huge waves to save a 40-foot fishing boat that has lost all power.

In Portrush, Co Antrim, the crew race to rescue a boy who has got into difficulties after jumping off rocks, and one of the crew volunteers enters the water to save him. On the Pembrokeshire coast, the lifeguard team at Whitesands Beach join forces with the St David lifeboat crew to rescue someone who has been found unconscious in the water

In Newhaven, the RNLI volunteers race to the rescue of two paragliders who have landed on an isolated stretch of beach and are now being swamped by the rapidly rising tide.

In Swanage, the lifeboat crew work hand in hand with the specialist coastguard rope team to help an injured climber.

In Lyme Regis, the crew face a frantic search for three fishermen whose boat has capsized in the River Axe. Meanwhile, the Kinsale crew help a skipper attempting to sail across the Atlantic.

On Ireland’s north west coast, the RNLI crew at Bundoran race to the rescue of a teenage girl who has been swept out to sea.

On the coast of south Wales, Penarth crew member Tom is called up for his first ever shout when a female paddleboarder is caught out by the tide.

In Eastbourne, on the Sussex coast, a routine day at the lifeboat station changes in an instant when a boat catches fire just outside the harbour.

In Swanage, on the Dorset coast, the RNLI crew race to the rescue of a diver whose life hangs in the balance.

In Thurso, Scotland’s most northerly mainland station, the crew race to the rescue of an ocean-going rower who has run into trouble 40 miles out to sea.

In Kinghorn, on Scotland’s east coast, a simple call out for the RNLI crew to a paddleboarder in difficulty isn’t all that it seems.

In Baltimore, south west Ireland, the crew are called out to reports of a solo sailor clinging onto his upturned catamaran over 70 miles out to sea.

In Calshot, the RNLI crew are called out to a young man who has lost consciousness in a jet ski accident; when his heart stops, it’s a race against time to bring him back to life.

In Whitby, North Yorkshire, the RNLI crew race to the rescue of two fossil hunters who are cut off by the tide - and soon find that they too are in grave danger.

When reports come in of a kayaker who has failed to make it back to shore - where his wife is watching on helplessly - the Larne crew race to the rescue.

In north Wales, the Conwy crew respond to reports of two people - including a young boy - who have been caught out by the tide and are now struggling to stay afloat.

In Plymouth, the crew race to the rescue of a fisherman who’s fallen off his boat and is now adrift in the water, with a sea temperature of just eight degrees. In Llandudno - Wales’s largest seaside resort - a father and son have capsized from their kayak on its very first outing. In the ancient harbour town of Wick, in north east Scotland, a photographer is cut off by the tide on some remote rocks, with night drawing in. And just down the coast in Fraserburgh, the crew have to deploy their inflatable Y boat to rescue a fisherman whose boat has run aground on a rapidly shrinking reef.

In Torbay, Devon, a yacht has sent out a mayday, meaning the lives of the six crew on board are in grave and imminent danger. In Wales, the Aberystwyth crew race to the rescue of a small boat that has lost engine power and is drifting perilously close to the rocks at the end of the harbour wall. In Dover, the crew launch their Severn-class lifeboat, after reports that a small boat - with 30 people on board - has capsized in the English Channel. On the north east coast of England, in Cleethorpes, a man is cut off by the tide in a notorious trouble spot. And on the Sussex coast, the Eastbourne crew respond to an unusual call out: a deer in the water...

In Blackpool, the crew respond to reports of a teenager who has been swept out to sea within sight of the main beach. On the Kent coast, the Margate crew begin a frantic search to find two paddleboarders - a father and son - who have drifted two miles out to sea. In Porthcawl, a crew member’s wedding is interrupted when the pagers sound for two people cut off by the tide. And in Dunbar, on Scotland’s east coast, the crew receive reports of a dog stranded on rocks, hundreds of metres from its owner on shore.

On the north eastern tip of the Scottish mainland, the crew at Wick begin a frantic search to find a paddleboarder who has drifted a mile out to sea, while her family wait anxiously on the shore. Further south, the Fraserburgh crew respond to a mayday call from a trawler that has run aground with four fishermen on board. In Mudeford, on the Dorset coast, the crew race to the rescue of a small inflatable boat that’s struggling to make it back to harbour in 40mph winds. On the Kent coast, a bystander has reported a capsized catamaran a mile out to sea. And in Rhyl, a Christmas Day call out to a person in the water leads to an unexpected discovery.

The North Berwick crew race out to try and save a windsurfer battling the seas as he and they fight the gale-force winds of Storm Dennis on the east coast of Scotland. In Carrybridge, on the banks of Lough Erne, Northern Ireland, the crew face two very different challenges: a man who’s become trapped under a digger on one of the lough’s islands and a cow that’s become stuck in the mud on the shoreline. And in Dorset, the Lymington crew race to the rescue of an elderly casualty whose yacht is caught on a lobster pot and is at risk of being overwhelmed by the stormy seas.

On the Isle of Wight, the Bembridge crew face a race against time to save an old fishing trawler that’s become trapped on a submarine barrier, and is now taking on water. Just across the island, the Cowes crew embark on a night time search for a missing jet skier. In Anstruther, on the east coast of Scotland, a man is badly injured after falling into the harbour just a few hundred feet from the station. And on the Welsh coast, the St Davids crew work with the local coastguard team to rescue two people who are stuck on a cliff.

Dermot O’Leary uncovers the story of the RNLI’s heroic efforts in the Second World War, as its crews were called to serve in the most perilous of conditions, saving 6,376 lives.

In Dungeness, the crew are called out to reports of a small boat in the middle of the shipping lanes, and they discover that the casualty is the subject of a major manhunt.

In Porthcawl, a fisherman has been dragged lifeless out of the sea by bystanders. The lifeboat crew race to the beach and join the desperate attempts to resuscitate him.

In Castletownbere, crew member Donagh faces a baptism of fire on his first ever shout as the crew carry out a dramatic rescue of a fisherman who’s suffered a suspected stroke.

In Queensferry, on the east coast of Scotland, an American visitor is caught out by the tide and is barely conscious when the RNLI crew drag him out of the water.

In Humber, the crew must work closely together to pull off the dangerous medivac of a fisherman with a spinal injury.

In Walmer, the crew respond to reports of a major incident involving a small boat in the Channel. On arrival, they are faced with mass casualties in the freezing water.

In Mudeford, on the Dorset coast, a search for a missing kayaker quickly escalates when it emerges that there are six more kayaks unaccounted for.

On the north Somerset coast, the Minehead crew come close to disaster in a challenging rescue of two walkers cut off by the tide.

In Porthcawl, on the south-west coast of Wales, the crew receive a call about a swimmer who’s been swept out to sea in a rip current - as his wife and son watch on helplessly.