constant weight bi-fins

{{Short description|Competitive freediving discipline}}

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.{{Cite web|last=AIDA International|title=Competition Rules Update|url=https://www.aidainternational.org/PostDetails/78|url-status=live|archive-url=https://web.archive.org/web/20210119085555/https://www.aidainternational.org/PostDetails/78 |archive-date=2021-01-19 }}

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.{{Cite web|title=AIDA Announces Freediving Competition Rules Changes - DeeperBlue.com|url=https://www.deeperblue.com/aida-announces-freediving-competition-rules-changes/|access-date=2021-09-21|website=www.deeperblue.com|language=en-US}} Following the rule changes, national record and world record titles could now be earned for the category of CWTB.{{Cite web|title=Colombian Sofia Gomez Uribe Sets New CMAS Constant Weight (Bi-Fins) World Record - DeeperBlue.com|url=https://www.deeperblue.com/colombian-sofia-gomez-uribe-sets-new-cmas-constant-weight-bi-fins-world-record/|access-date=2021-09-21|website=www.deeperblue.com|language=en-US}}

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.{{Cite web|title=CMAS Freediving Competition Archives|url=https://www.cmas.org/apnoea/championships-archive|url-status=live|archive-url=https://web.archive.org/web/20121030231340/http://www.cmas.org/apnoea/championships-archive |archive-date=2012-10-30 }}