At times I&rsquom convinced he&rsquos a non-human swimming robot,&rdquo river guide Matthew Mohlke says of Martin Strel, and you can see why. Strel, the Slovenian endurance swimmer, is a fearless conqueror of great rivers, the holder of the Guinness records for swimming the Yangtze, the Mississippi, the Danube and finally, in 2007, the Amazon. This is an account of the last of those marathons, a potentially deadly 3,274-mile journey in 66 days.

This isn&rsquot a travel book in the conventional sense we learn the names of various anchoring spots along the river in Peru, Brazil and Colombia, but no real details about most of these places &mdash which aren&rsquot exactly tourist attractions anyway It&rsquos more a collection of daily journal entries, which makes for a quick read, but also a somewhat repetitive one &mdash for all the fear of river pirates, crocodiles and other predators, there are days when nothing very exciting happens. However, Mohlke gets around this by detailing the little challenges facing the crew on the support boat outdated maps (in terrain that can barely be mapped anyway) the need to store buckets of rancid pig&rsquos blood, used to divert attacking piranhas constant bouts with illness the shifting moods and personal equations on board.

He gives us snippets about Strel&rsquos life and describes how he deals with the exhausting swims by retreating into personal memory palaces and telling himself stories. Even as the support crew is armed with laptops and other modern equipment (something Mohlke admits to feeling ambivalent about, because it takes away some of the purity of this primal journey), Strel single-mindedly ploughs on, spending up to 12 hours in the water each day. &ldquoIt&rsquos just him and the river. It&rsquos like he&rsquos the only one left on the planet who&rsquos still living like a caveman.&rdquo This is a lightweight book, but at its best it creates a vivid portrait of a portly, middle-aged man who dreamt a mad dream and then went on to live it.