Why does swimming sideways work?

A rip current is a powerful, narrow channel of fast-moving water that flows away from the beach. Rip currents form on ocean beaches and even on the shores of large lakes, and they can move at up to about 2.4 metres a second, faster than an Olympic swimmer.

They are a serious danger. In the United States alone, lifeguards carry out tens of thousands of rescues from rip currents every year, and about 100 people die in them.

What makes them so dangerous is often the swimmer's own reaction. Someone caught in a rip current feels themselves being pulled away from the shore and, in a panic, tries to swim straight back against it. Even a strong swimmer cannot beat the current this way. Fighting it only wears the swimmer out, and an exhausted swimmer can drown.

The right thing to do is not to fight. Instead, swim parallel to the shore, across the current rather than against it. Because a rip current is narrow, swimming sideways soon carries you out of it. Then swim back to land at an angle.

A rip current is not the same thing as a rip tide. A rip tide is a strong flow of water caused by the tide, moving through a narrow opening such as the mouth of an inlet.