The bikes were left at home last Sunday when the first race in the South East Regional Junior Triathlon Series took place in Gillingham, Kent.
Eight Atlantis swimmers faced the event which consisted of a swim and a run, known as an aquathlon.
The Horsham-based club came home with both individual and team honours.
Excellent performances in the youth category saw Gemma Cumber post the fastest swim and Gaby Eltham take first place in her first ever multi-sport event.
In TriStar 3 girls, Evie Clarke and Amelia Wright ensured a one-two for Atlantis, with Sam Clarke featuring strongly in TriStar 3 boys.
Will Carey won TriStar 2 boys with Isabella Hayes and Ethel Whyman also recording fast times in the TriStar 2 girls section.
Atlantis were narrowly beaten into second place for the overall team trophy by home club Medway Tri, but succeeded in pushing triathlon specialists, Bodyworks XTC of Eastbourne, into third.
Next stop is East Grinstead in May for the first full triathlon of the South East season.