Hydroplane means to skim or glide across the surface of water instead of pushing through it. When a speedboat goes fast enough, it rises up and hydroplanes, riding on top of the water like a stone skipping across a pond. Racing boats are designed to hydroplane, which lets them reach incredible speeds because they're barely touching the water.

The word also describes something dangerous that can happen when cars drive too fast in heavy rain. When tires can't push water out of the way quickly enough, the car starts hydroplaning: it loses contact with the road and slides along on a thin layer of water instead. During hydroplaning, the driver temporarily loses control because the tires can't grip the pavement. This is why drivers slow down in wet conditions.

A hydroplane can also be a type of fast motorboat built specifically for racing. These boats have special flat-bottomed hulls designed to lift up and skim across the water at high speeds. Hydroplane racing became popular in the early 1900s and remains an exciting sport today, with boats sometimes reaching speeds of over 200 miles per hour.