The Combined Lions Clubs of Darwin are hosting the 32nd regatta and are hoping to raise enough money to buy a new ambulance.
About 15,000 people are expected to turn out for the day.
The action kicks off at 10am ACST this morning with events including a tug of war, thong throwing competition, sand castle building and the regatta.
Organiser Cedric Lawrence says they are raising funds for the St John Volunteer Ambulance.
"We're hoping to raise $50,000 - it's only a gold coin donation to enter," he said.
"It's a donation, so no one has to pay a fee at all, but we'd love everyone to pay the gold coin donation so it increases our intake this year to help us make that $50,000."
Mr Lawrence says Mindil is hosting more than just the regatta.
"There are lots of family and children's and community events that take place on the beach also like the tug of war, the children's races, the children's sand castle buildings," he said.