Intrepid rowers took over a Wandsworth gym as they begun two brutal world record attempts, pushing themselves to the limit to row 1m metres.
Mark Gleeson , Jack Carter and Nick Kempster will cover two million metres in their combined challenges.
Mr Kempster, who is attempting to break the record for the ‘individual million metres row’, started at roughly 1.15pm on Tuesday.
The 24-year-old will row relentlessly to beat the current best time of eight days, five hours and 41 seconds, only planning short breaks to eat and sleep.
Mr Gleeson and Mr Carter will try and break the record for the tandem million metres row, and will begin their challenge on either Thursday or Friday.
The current best time stands at three days, ten hours, 33 minutes and 19.5 seconds
The three men will all use rowing machines at the PureGym in Wandsworth High Street.
Mr Gleeson, who is the head of the Kings College London rowing team, said: "Nick has a very good chance. It’s going to be physically and mentally tough, but for him it is achievable.
"Mine and Jack’s will be equally as gruelling. It nerves me because this is not going to be a walk in the park."
The epic challenge however is just a warm up for a rowing race that will take them across the Pacific.
Mr Gleeson, Mr Carter, Mr Kempster and Chris Blacketer form ‘Noman’ rowing team, who will take on the Great Pacific Race, a 2,400 mile, month-long slog from California to Hawaii.
The four-man crew, who set off on June 7, is aiming to raise £200,000 for the Noman cancer charity, which is fighting to eliminate the Human Papillomavirus (HPV) responsible for 5 per cent of all cancers.
They have already raised roughly £50,000.
'Oar-inspiring': (From Left) Jack Carter, Mark Gleeson, Chris Blacketer, Nicholas Kempster
Mr Gleeson, who lived in Balham up until last year, said: "It's not for the faint-hearted, it is going to be something completely different to what we are used to.
"We will probably lose around 12 to 24kg in weight so we will not be the same people when we return."
To make a donation visit: https://mydonate.bt.com/fundraisers/noman2014
Noman's land: The team will race across the Pacific Ocean for 30-40 days