Swimmers brave Fannie Bay for race after crocodile sighting

More 150 brave competitors will take to the water for the Fannie Bay Ocean Swim this afternoon, despite a crocodile sighting at East Point last weekend.

Entrants as young as 13 will choose from a 1.2km or 2.1km course, with many stating paddling out into croc-infested waters "only adds to the thrill of the competition".

Rangers patrolled the sea in the nights leading up to the 13th annual race, with organisers prepared to cancel the event if there were any crocodiles lurking.

But Darwin Surf Life Saving Club president Ray Hall was confident the large-scale firework activity for Territory Day the night before had scared the reptiles away.

"Lots of noise, lights and boats on the water has a big impact," Mr Hall said.

Mr Hall said the 30 life guard volunteers on surf skis and boards in the bay will also deter any curious crocs.

He said the risks were worth it for the "bragging rights".

At the starting line, three-time competitor Charles Douglas said he wasn't fazed by the threat.

"I'll swim as fast as I can anyway, the thought of a croc chasing me isn't going to add much to my speed," he said.