People can swim in any body of water large enough to permit free movement. These areas include ponds, lakes, rivers, the ocean, and pools. Most people enjoy swimming in water that is between 18° and 29°C (64° and 84°F).
The act of moving through the water by using the arms, legs, and body in motions called strokes. Beginners first put their heads in the water and blow bubbles by exhaling. Gradually, students progress to floating, treading water, and ultimately, learning the techniques of the major strokes. The most common strokes are the crawl, backstroke, breaststroke, butterfly, and sidestroke.
Swimmers must follow the instructions of lifeguards and obey posted information about water conditions, tides and other dangers.
For inexperienced recreational swimmers, many safety hazards exist-even in a pool. These hazards include misjudging a dive and hitting one’s head on the bottom, holding one’s breath too long and experiencing sudden cramps.
In rivers and oceans, all swimmers should respect the power of nature. Powerful waves, tides, and currents can easily overpower even the most experienced swimmers, sweeping them out beyond safety or throwing them into coral or rocks.