Why are they swimming in the river, especially one that flows through a big city and is certain to be polluted? I thought Olympic water sports were held in swimming pools.
triathlon - An athletic contest in which participants compete without stopping in three successive events, usually long-distance swimming, bicycling, and running.
Triathletes swim 2.2 miles. That’d be really boring in a lap pool.
They could have relocated the triathlon to a cleaner river, or the same river nearer the coast