Why should you start your dive slightly negative?

Starting your dive slightly negative is important because it allows for better buoyancy control during the descent and ascent phases of the dive. A diver who is slightly negative can comfortably descend to the desired depth and control their buoyancy more effectively as they begin to breathe and adjust their gas. As a diver exhales, they may become neutrally buoyant, or even slightly positive. This technique also prepares the diver to manage their buoyancy actively, using their breathing to fine-tune their position in the water column.

Buoyancy management is critical for underwater stability and safety during dives, particularly when spending extended periods at deeper depths known to cause varying buoyancy challenges. Therefore, starting slightly negative sets a solid foundation for maintaining control throughout the dive.