Thousands of swimmers are taking to the pool at Les Quennevais to raise money for charity.
Islanders of all ages are being sponsored to swim lengths, with the money raised split between nine charities promoting outdoor wellbeing.
The event has raised more than £3.8 million over the past 50 years.
More than 400 teams from businesses, schools and charities have signed to up to take the plunge.
Students from Rouge Bouillon and De La Salle schools have been among the first to get in the pool.
The chosen charities to benefit this year are Brighter Futures, Beach Ability, Jersey Mencap, Jersey Sea Cadets, Acorn Enterprises, Autism Jersey, Wet Wheels Jersey, Healing Waves and Les Amis.
Swimarathon runs from 13 to 17 March 2024.
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