They are chasing a bounty of £100,000 for rowing 2,000 miles round the coast of Britain, braving treacherous tides and some of the most dangerous shipping lanes on the planet.
As many as 15 boats are expected to take part in the gruelling race - GB Row 2013 - which starts at Tower Bridge in London on June 1 next year.
Already 10 crews - with a total of 40 rowers - are in training to win the bounty - awarded to the first team that can beat the existing world record of 26 days to complete the tortuous race.
The teams - made up of two, four or eight oarsmen and women - will row non-stop and unassisted from London, around Land's End, up to John O'Groats and back to the capital.
They will all be trying to beat the world record of 26 days and 14 hours and 12 minutes set in 2005 by a four-man crew from the Grenadier Guards who were almost drowned when their boat, no bigger than a family car, was hit by a Force Ten storm in the Irish Sea.
Among the 10 boats already committed to next year's race is a crew of four rowers from the three armed services, led by Major James Coleby, of the Coldstream Guards.
Former Royal Navy Commander David Hosking has also registered a four-man team who will be undergoing sea trials in December.
Other competitors also include Polar explorer and mountaineer Clare Shouksmith, who is leading a mixed crew of three men and a woman in their ocean rowing boat, Pure Gym.
Clare, 23, from Poole, Dorset, said: "GB Row pushes the boundaries of extreme challenges - in fact, more people have walked on the moon than have successfully rowed around the Great British coastline!"
And Heather Rees-Gaunt, 36, from west Wales will skipper a team of men and women made up of rowers who race Celtic longboats.
Other teams racing around the UK coast include an eight-man crew, to be led by skipper Leven Brown, from Melrose in the Scottish Borders, who in 2010 set a new world record for rowing across the Atlantic, knocking 11 days off the previous best time.
Next year Leven, 40, will row 3,000 miles across the Atlantic in January, then race 2,000 miles around Britain in June, before flying to Australia to row 5,000 miles across the Indian Ocean in July.
Four rowers from Edinburgh, led by lecturer in neurosurgery Mark Hughes, will race as H2rOw in a 23-feet-long ocean rowing boat Fight & Spirit.
Charlene Ayres, from Pontyclun, south Wales and her partner Adam Lewis hope to become the first mixed pair of rowers to circumnavigate Britain, while Jason McKinley, who has already rowed across the Atlantic, and Josh Tarr aim to complete the gruelling race as a two-man team in their boat, Savoir Faire.
Gym owner Jason, 42, from Salcombe, Devon, said: "I like a challenge, an adventure and a chance to achieve something few others have. I crossed the Atlantic in 2003 as a pair. I believe a pair rowing around Britain will have more success than a team of four or six."
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