Deep diving can be classified as anything over 30 metres in depth. At this point special precautions have to be taken as the body reacts to the external water pressure in a number of ways.
- A scuba diver needs more oxygen at higher pressures, AT 50 metres a diver will need to breathe six time the amount of oxygen than normal.
- Nitrogen can become stored in the body during long, deep dives. Nitrogen narcosis can set in and is deadly as such depths.
- Decompression stops will be necessary before returning to the surface. A diver must have sufficient oxygen to allow for these stops.
- Tidal currents can move a diver away from his starting point, particularly during lengthy decompression stops.
- There is risk of oxygen toxicity caused by breathing in too much of this gas. If affected divers go into convulsions and drown.
- Carbon Dioxide poisoning can occur at depth when not enough of this gas is expelled due to the effort involved in breathing
These risks can only be negated with comprehensive training, practice and advance planning. The benefits of deep diving include larger, more exotic and brighter coloured fish species can be seen. Furthermore, deeper, less explored parts of wrecks and caves can be explored.