Here's a scuba diver making friends with a fish!
Click on image for full size
Courtesy of Corel Photography
Scuba stands for self-contained, underwater breathing apparatus. It means that scuba divers carry all of the breathing medium they need with them for the duration they are underwater. Open-Circuit scuba is different than Closed-Circuit scuba and Semi-Closed Circuit scuba.
In Closed-Circuit scuba there is a total recirculation of the gas supplied to the diver. In Semi-Closed Circuit scuba, some of the gas is reused by the diver. In contrast, the gas supplied during Open-Circuit scuba is not recycled at all. When a diver breathes out, the exhalation goes out to the surrounding water instead of being recirculated somehow.
In Closed-Circuit scuba, oxygen and mixed gas are used as the gas supply for the diver. In Semi-Closed Circuit scuba, mixed gas is used as the gas supply. In contrast, Open-Circuit scuba uses mixed gas and air as the gas supplies, with air being the main gas supply for Open-Circuit scuba divers.
There are risks involved in all kinds of scuba diving. Adequate training, experience, the presence of a dive buddy, and observation of dive tables should minimize the risks so that Open-Circuit can be a safe and enjoyable experience.
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