Aleksander Doba, who sports a foot-long greying beard and broad smile, was named a National Geographic adventurer of the year in 2015 for what the magazine said was the longest open-water kayaking expedition across the Atlantic in history.
That six-month voyage saw him set off from Lisbon in October 2013 and arrive in Florida in April the following year, navigating ocean swells and tempestuous weather.
"Dozens of sharks checked on me, but one was ready to attack me, and I had to whack his head with the paddle really hard to make him leave," Doba told National Geographic.
He will set off in the 21-foot (over six metre) white and yellow kayak he calls "Olo" on May 29 from New York and hopes to arrive in Lisbon in August or September.
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He first paddled across the Atlantic between October 2010 and February 2011, across one of the narrowest points of the ocean from Senegalese capital Dakar to the Brazilian city of Acarau.
He later rafted along the Amazon in Peru but had to abort the mission after encountering bandits.
Altogether he has logged 96,000 kilometres by kayak and said today that he is looking forward to seeing "my counter pass the 100,000-kilometre threshold" this year.
The sportsman is also an avid rock-climber, parachutist, glider pilot, sailor and yacht skipper.