Constant Weight (CWT) is the most widely practiced depth discipline in freediving. The FreeDiver descends vertically along a diving line and rises to the surface, using either monofin or bi-fin and/or arm pulls. It cannot be used to pull the diving rope, and the diver is only allowed to hold it once while turning the bottom and preparing for the ascent. As the name of this discipline suggests, the diver cannot change the amount of fixed weight used during the dive.
Constant Weight Without Fins (CNF) requires divers to use only muscle strength to get themselves to the bottom and up. A free diver normally descends in a breaststroke quite similarly to what swimmers do. Just like in the CWT, the diver is not allowed to pull the rope or change the weight used. CNF is considered the most difficult of the three competitive depth disciplines.
Free Immersion (FIM) is similar to a (CNF) dive without a fins, as the amount of weight remains the same during the dive and the diver cannot use any fin-like propulsion material. Alternatively, in FIM, the diver can pull the guide rope to ascend and descend. FIM is considered one of the more relaxing disciplines because the technique is so easy to learn, the diver can use both the "head down" and "head up" position and descend as slowly as he wants. FIM is also a great discipline for developing ear equalization skills.
The following two disciplines are generally accepted non-competition disciplines, meaning that divers can also only set individual record attempts instead of competing against each other on the same day.
Variable Weight (VWT) is a discipline in which the free diver can vary the amount of weight used during descent and ascent. This is a discipline that allows divers to descend using a diving sled and then to surface by pulling the rope up with the help of a monofin, bi-fin or body force.
No Limits (NL) is the deepest discipline in freediving. Here, the diver also uses a sled or other type of ballast weight to make a rapid descent and then use a balloon or similar buoyancy device to ascend. This discipline basically requires good balancing technique and pressure tolerance, as the freediver does not have to use his own energy to descend and ascend. New No Limits events are currently not approved by AIDA due to the ever-increasing risks divers put themselves in danger to reach depths in excess of 200 metres.