How Fast Is Michael Phelps Swimming?

The most decorated Olympian sustains around 2.3 m/s in competition. Despite superhuman technique, elite humans are surprisingly slow swimmers compared to fish — we simply aren't built for water. Phelps's wingspan exceeds his height by 8 cm, an unusual proportion that helps.

Phelps won 23 Olympic gold medals — more than most countries have ever won in their entire history.

• A dolphin swims 5× faster
• A sailfish is 13× faster still