Boris Mavra is an open water swimmer from the United Kingdom. He successfully completed a crossing of the English Channel on 26 July 2011 in 11 hours 59 minutes.
He serves as the Chairman of the Channel Swimming & Piloting Federation.
He he is a member of the Frequent Flyers, a 6-person relay from Great Britain and Germany that attempted a 69 km (49 mile) all butterfly 6-person relay in Lake Geneva, Switzerland. They finished with an unratified time of 33 hours 34 minutes 9 seconds on 13-14 July 2016. The team consisted ofMark Johansen, Kevin Blick, Sam Mould, Robert Fisher, Rob Ouldcott, and Boris Mavra. Their unprecedented attempt using butterfly faced primal and dangerous conditions including predominant headwinds exceeding 32 knots. The relay decided to change to freestyle in the interests of safety after nearly 13 hours. He competed in the 2016 19 km International Jarak-Šabac Marathon Swim (Plivački maraton Jarak-Šabac) in Serbia.