The Seine River in Paris was so clean that it was chosen for a special swimming, biking, and running race called a triathlon.
Two French athletes, Cassandre and Léo, won medals for their country, making everyone very happy.
The river was cleaned up by making it safe for swimming, which took many years and a lot of money.
Many people came to watch the races and cheer for the athletes, making it a big celebration for Paris.
