According to Official Guinness Records,
The youngest person to row three different oceans is Fiann Paul (Iceland, b. 15 August 1980), who was 35 years 325 days old on 5 June 2016, when he started a Mid-Pacific row from Monterey, California to O'ahu, Hawaii, USA, as part of a team of four, on board Danielle. The team reached their destination on 14 July, setting an overall speed record (2.21 knots) for the route in the process. Fiann had previously rowed the Atlantic east to west (2011, in a team of six, on board Sara G) and the Indian Ocean east to west (2014, in a team of seven, on board Avalon).
For a complete list of 2016 records, please visit 2016 Guinness Records in United States.