Bi fins

Bifins also known by its acronym, BF or as stereofins is swimming on the surface of water with mask, snorkel and a pair of fins using a crawling style. BF races are held for distances of 50, 100 and 200 m in swimming pools and over various long distances in the openwater environment such as 4 km and 6 km. It is reported that BF was introduced in 2006 to provide the opportunity for competition by swimmers who cannot afford to purchase a set of monofins. Swimmers must remain on the surface of the water at all times for the duration of the race except when starting or make a turns at the end of a swimming pool where an immersion of a distance of 15m is permitted.