The challenge began in Hraunhafnartangi on Friday and ended in Hallgrimskirkja, Reykjavík, with athletes individually running day and night.
Mr Cook said: “Being part of a team to complete some serious miles in such a harsh climate has been an incredible experience that really pushed me to run faster and harder than ever before.”
The others in the relay challenge were William Goodge, who claimed to have broken the world record for running across the width of Australia, GB runner Alfie Manthorpe, Hercules Nicolaou, who ran across the Adriatic Coast and Hyrox athletes Jake Dearden and Lucy Davis.
They were led by George Heaton, the co-founder of fashion brand Represent, which organised the challenge.
Mr Heaton said: “Running over 600km in some of the most unforgiving terrain in the world is something that I knew would be hard, but definitely in reach.
“I wouldn’t have been able to achieve this without running alongside the best team in the world, Team 247.”