Cseh was trying to keep pace with fellow competitors like US swimmer Michael Phelps, the Olympian who has won the most gold medals ever (22 and counting). Phelps won the 200-meter butterfly by just .04 of a second — the closest margin of victory in history. “He led the whole way, but guys were chasing him right down to the end,” said Pretty about Phelps. “One of the best displays of swimming I’ve ever seen.”

Excerpt from: 

Making a splash in Rio: Robots snap underwater shots at Olympics – CNET