What does CNF mean?
CMAS calls the open water depth discipline Constant Weight with no fins, or CNF. The athlete keeps the same weight throughout the attempt and does not use fins. Its overview also says the athlete may not pull on the performance line.
William Trubridge introduces himself in the Orca Group Series as a freediver who specialises in no fins. He explains that the athletes do not have “any propulsive assistance at all.” His description keeps the focus on the body’s own movement, rather than equipment doing the work.
He also describes bringing a tag back to the surface. That return is part of the account he gives, so his explanation is more useful than a photograph of a diver at a particular depth.
How is it different from free immersion?
Free immersion, or FIM, also uses no fins. The distinction in the CMAS overview is that line pulling is allowed. Seeing a diver without fins is therefore not enough to identify the discipline.
This is a useful question to bring to an interview or competition broadcast: what is the event called? The full name tells you more than the appearance of the equipment.
Why does constant weight matter?
Constant weight describes the weight remaining unchanged throughout the attempt. It is part of the event definition, rather than a general description of every form of freediving.
In William’s introduction, the name of his speciality gives the listener a frame for the conversation that follows. It is a description of what he does, not a claim that every freediver competes in the same event.
The pool event has a different name
CMAS separately lists Dynamic without Fins, or DNF, for horizontal distance in a pool. That differs from the depth attempt in open water described by CNF.
The small difference between those names matters when a short clip leaves out the wider explanation. Keep the discipline and the setting together before assuming that two performances are comparable.
Hear William’s explanation
Keep the introduction in the context of his full conversation with Nick Long.
Sources and further reading
The definitions on this page follow the CMAS overview. They describe event names, rather than replacing the complete competition rules.