Beach safety should start before you even set off for the beach. If you are visiting a resort, ask if and when the beaches are patrolled, and question local lifeguards about water quality. At unattended stretches of beach, you need to be able to identify potential problems.
Barely an episode of Baywatch goes by without mention of a rip - not the product of an overstretched Lycra bathing suit, but a major source of surf-related accidents. Rip currents are typically formed by a body of water approaching the shore; the water level is built up and the water is then sucked rapidly back out to sea. Such currents are usually associated with wave action: the larger the waves, the more powerful the rip.
Before entering the water, have a look at the wave patterns. Rip currents can usually be identified by a large streak of discoloured water extending from the shore beyond the surf line. This is easy in otherwise crystal- clear waters, less so in the brown windsor soup on some British beaches. Other signs to look for include waves breaking further out from the beach, at the edges of the track of water forming the rip; debris such as weed stretching out from the shore in a parallel tract; or a similar tract of foam extending beyond the surf line.
Sometimes a rip can occur with little or no warning. If you get caught in one, don't panic. A swimmer of limited ability should ride with the current and swim parallel to the beach for 30 or 40 yards, then swim to shore on a perpendicular course. Strong swimmers should swim at a 45-degree angle across the rip, and in the same direction as the prevailing side current.
Breaking waves are potentially lethal. Plunging waves, known as "dumpers", break with tremendous force and can throw an adult straight to the shallow bottom. When large plunging waves are seen at the edge of the beach even experienced swimmers should take care; children should not be allowed into the water.
Surging waves, which never break as they approach a beach, contain an enormous amount of energy. They can carry swimmers out into deeper waters, and are especially dangerous around rocks. Turn sideways to reduce the wave's impact, or dive beneath it and keep as flat to the sand as you can before surfacing.
Finally, there is the question of chill factor. The human body temperature is 37F. British beaches are not. At the onset of shivering, leave the water. Children are particularly susceptible to hypothermia.
Some swimmers think vigorous exercise is the way to stay warm, but exercise in water cooler than 24F accelerates the fall in body temperature. If you swim with an elevated blood-alcohol level - anything up to 20 hours since your last drink - hypothermia is a bigger risk.
Dr Steve Ray
Steve Ray is a former lifeboatman and currently lectures in physiology at Oxford University