In this short film, the sports engineer Steve Haake takes you beneath the surface of professional swimming. Haake explains how science and technology have helped top swimmers to get around the fact that humans are not adapted for water. He dives in and addresses some of the big questions in the world of swimming, such as whether there is such a thing as "fast water" and why the international governing body of swimming has decided to ban the full-body swimsuits that led to so many world records falling a few years ago.

You can also watch the two other films in this series on the physics and technology of professional sport, which focus on running and cycling. And for a limited period you can download a free copy of the July issue of Physics World, a special edition that looks at the physics of sport. It includes features on the physical principles underpinning athletics, and the roles technology plays in enabling and enhancing sporting performance.