A record attempt will be made off north Queensland this weekend for the world's largest nude snorkel.

The event is being held in waters off Magnetic Island near Townsville with more than 500 people expected on the island.

Coordinator Barbara Gibbs says it is about raising awareness of ocean health.

"Our Magnetic Island is just like a boat in an ocean; we're surrounded by it and it's very important for us to look after that and not dirty our backyard," she said.

"We need to make sure we're not part of the problem and we need to fix up whatever problems we do have around with pollution or whatever, even these little tiny bits of plastic that the birds and the fish eat, and the plastic bags the turtles and crocodiles eat.

"This is our second World Oceans Day and this is also the second United Nations-sanctioned World Oceans Day."