Before his Olympic debut, Sethsothorn left his native country Thailand for a two-year residency in the United States.

He also trained, along with two other swimmers Juan Veloz of Mexico and Carlo Piccio of the Philippines, for Davie Nadadores Club under head coach Terry Stoddard.

[2] While swimming for his respective club, Sethsothorn had earned numerous high school titles including his first triumph from the Mission Viejo Invitational in 2000.

[4][5] In the 400 m freestyle, held on the first day of the Games, Sethsothorn posted a lifetime best of 3:56.68 to lead the third heat, finishing twenty-fourth from the prelims.

[9] In his final event, 1500 m freestyle, Sethsothorn challenged seven other swimmers in heat three, including top favorites Ricardo Monasterio of Venezuela and Spyridon Gianniotis of Greece.