“Although humans have been swimming for thousands of years, swimming only became a competitive sport in the early 1800s. Today, swimming is the third most-watched sport in the Olympic Games.
Crossing the English Channel
In 1875, Matthew Webb ignited public interest in swimming when he became the first person to swim across the English Channel. Swimming only breaststroke, it took him more than 21 hours to complete this feat. Thirty-one years would pass before another person would successfully swim across the Channel.
The Debut of Modern Olympic Swimming
In the first modern Olympic Games in 1896, men competed in four swimming events, all contested in the choppy open water of the Mediterranean Sea. Four years later at the 1900 Summer Games in Paris, all the swimming events (which included an obstacle course) were contested in the Seine River.
Source: History of Swimming – Swimoutlet