Just For Fun

Controlling Buoyancy Underwater

To dive safely, divers must control their rate of descent and ascent in the water. Ignoring other forces such as water currents and swimming, the diver's overall buoyancy determines whether he ascends or descends. Equipment such as the diving weighting systems, diving suits and buoyancy compensator's can be used to adjust the overall buoyancy. When divers want to remain at constant depth, they try to achieve neutral buoyancy. This minimizes gas consumption caused by swimming to maintain depth.
The downward force on the diver is the weight of the diver and his equipment minus the weight of the same volume of the liquid that he is displacing; if the result is negative, that force is upwards. The buoyancy of any object immersed in water is also affected by the density of the water. The density of fresh water is about 3% less than that of ocean water. Therefore, divers who are neutrally buoyant at one dive destination (e.g. a fresh water lake) will predictably be positively or negatively buoyant at destinations with different water densities (e.g. a tropical coral reef).

The main thing to remember with buoyancy is that you should always check your weight at the beginning of the dive so that you are comfortable throughout the entire dive. Use your fins to swim and hold your arms across your chest as shown in this picture. You will loose a lot less oxygen and be able to dive longer. Remember that buoyancy takes time to adjust to at first so don't get frustrated. In time you will learn all the tricks of the trade.