Constant weight bi-fins, denoted by the acronym CWTB in competition notation, is a competitive freediving discipline wherein the freediver wears a pair of bi-fins (or stereo, as opposed to a monofin) to descend along the line with or without the use of their arms. Pulling on the rope or changing ballast will result in disqualification; only a single hold of the rope is allowed in order to turn and stop the descent and start the ascent. The diver is prohibited from using a dolphin kick; doing so will result in disqualification of the day's dive.[1]

For AIDA International officiated freediving competitions, bi-fins was previously included under the umbrella term of constant weight (CWT) in competition. Prior to 2019, competitors wanting to use bi-fins in competition would compete under the category of constant weight alongside those using a monofin. In 2019, AIDA formally separated Constant Weight Apnea with Bi-fins (CWTB) into its own category for competition.[2][1] Following the rule changes, national record and world record titles could now be earned for the category of CWTB.[3]

For CMAS officiated freediving competitions, bi-fins has been recognized as a competitive category separate to constant weight (with a monofin), with officiated records for bi-fins starting as early as 2015.[4]

Current world record holders in CWTB




  1. ^ a b AIDA International. "Competition Rules Update". Archived from the original on 2021-01-19.
  2. ^ "AIDA Announces Freediving Competition Rules Changes -". Retrieved 2021-09-21.
  3. ^ "Colombian Sofia Gomez Uribe Sets New CMAS Constant Weight (Bi-Fins) World Record -". Retrieved 2021-09-21.
  4. ^ "CMAS Freediving Competition Archives". Archived from the original on 2012-10-30.
  5. ^ "Vertical Blue 2023 Day 1: Arnaud Jerald Sets New Freediving World Record -". Retrieved 2023-07-21.
  6. ^ "Alessia's IG". 2023-03-29.