A Newcastle man who lost his $40,000 prosthetic leg, specially designed for water sports, while jetskiing said he was hopeful it would be found.

A team of volunteer scuba divers has been searching Lake Macquarie for Toby Bird's leg which came off on Monday.

Mr Bird said the jet ski was stuck on full throttle when his leg dislodged, sinking within seconds.

"It is a racing jet ski and so it just went so quick. We got thrown off and when we just popped out of the water the jet ski is 50 metres one way and my mate is 50 metres the other way.

"I'm just like 'Oh bro, me leg just fell off'."

Mr Bird thanked a group of volunteer scuba divers who have searched for the leg since it sunk.

He said it was about six to eight kilograms in weight and would have sunk fairly quickly.

Mr Bird said he had another leg but it was not suitable for water sports.

"I've got an everyday bionic one that I use, but it's my water proof and sports one so without that I can't really do anything fun," he said.

"I've got my 19-month-old daughter and I take her to the beach a few days a week, but I can't do that. I am pretty much stuck on land now."

Diver said strong current hampering search

Bob Staddon is a high-speed drift diver and is among a group of divers who joined the search for Mr Bird's leg.

Toby Bird has thanked divers in the search for his prosthetic leg. ( Supplied: Facebook )

He said the current where the leg fell off is very strong and the prosthetic could be anywhere.

"We've got these big spring tides running at the moment and you can see the amount of sand and debris that is moving underwater," he said.

"There are truck tyres down there from the old dump in Swansea. We go down there and they are moving.

"These are semi-trailer tyres, so we are talking fairly heavy stuff."

A crowd funding page has been set up to raise funds for a new leg.

Mr Bird says if it is found he would donate the money raised to charity.