Hundreds of islanders of all ages are putting on their swimming caps and goggles over the next five days.
The 50th annual Swimarathon is taking place at Les Quennevais pool until Sunday 13 March, raising money to create a new community hub at Maison Des Landes.
Students from Helvetia House School got the event underway at 9am on Wednesday.
The Lieutenant-Governor got the Swimarathon underway
A short time later, Jersey's Lieutenant Governor, Air Chief Marshall Sir Stephen Dalton, presented a special award to sisters Pat Hingston and Angie de Carteret. They have taken part in every Swimarathon since the event began in 1972.
Other schools, businesses and organisations are putting forward teams over the coming days.
They're all aiming to raise a combined £50,000 to mark the fundraiser's 50th year.
Organiser and Lions' Club President, Bill Harris, says this year's Swimarathon marks a return to near post-Covid normality:
"We are delighted that the Swimarathon will be the event that we have all become used to over the past 50 years. We are very grateful for the support we have received to bring that about, from the Les Quennevais management, our sponsors and, above all, the 400+ islanders who are prepared to swim for charity."

Cheaper parcel prices for 2026
Draft Food Law lodged to protect people with allergies
WATCH: Last Blue Islands plane leaves Jersey
Jersey pupils secure places in STEM Racing UK National Finals
Plémont puffins get a Christmas makeover
New café bar and kitchen coming to Jersey Airport
Fresh process to choose Havre des Pas Lido operator
Jersey Water has 100% compliance in all water quality standards, including PFAS