Skin diving, or free diving, is the practice of diving underwater without the use of a portable air supply, as is common with scuba diving. Skin diving can be done with minimal equipment, such as a mask and snorkel, or it may be done with no equipment at all. Typically, the activity requires no additional skills, other than a knowledge of how to swim.
Due to the fact it requires no additional skills, skin diving is a popular activity for those visiting seaside resorts and taking cruises. Often, in these situations, it is called snorkeling. Cruises offer such adventures at nearly every port of call they go to in warm weather areas. Some resorts offer equipment for no additional charge.
Skin diving has the advantage of keeping divers closer to the surface so there is less of a worry about getting the bends. This is a potentially fatal condition caused when divers ascend too rapidly from deeper depths and nitrogen is released into the blood. Most of the time skin, because their air supply is at the surface, divers do not go down far enough where this would become a problem.
In some locations, individuals may become professional skin divers, where their jobs include gathering clams and checking fish nets. In many cases, these divers are able to stay underwater for minutes at a time. This is done by a technique called "packing." Using this strategy, a diver gulps like a fish as he finished breathing to compact as much air as possible into the lungs. Perfecting this technique takes a substantial amount of practice, and can be dangerous.
Skin diving is also a very popular in freshwater springs. These springs make it very easy for divers to see some of the natural freshwater wildlife. In many cases, lakes and rivers are too murky to enjoy diving to a great degree. The visibility is usually not a problem in natural springs, which are known for the clarity of their waters.
As with scuba diving, there are some precautions that should be taken when skin diving. For example there is a condition known as latent hypoxia, which can cause those holding their breath for long periods of time to black out. This often happens suddenly and without warning. It is especially common where divers are required to hold their breath. The best way to combat this problem is to always dive with a friend.