A DIVER was forced to seek refuge on a small island for 18 hours after his dinghy drifted away in gusty winds off Esperance.

Police held grave fears for Peter Agnew, 46, after he failed to return from a solo free-dive trip to Gunton Island, 15km southeast of Esperance on Friday.

Mr Agnew, with more than 1000 hours of diving experience, set out about 11am on Friday and anchored his boat as he went for a dive. When he resurfaced about an hour later the boat was gone.

Police say he swam to nearby Sandy Hook Island, where he stayed overnight. He spotted a fishing boat anchored off the island about 6.20am yesterday and swam to it for help.

"I shouted out, but they couldn't hear me , they were about 800m away. I just decided to swim to the boat," Mr Agnew said. "I climbed up the back and gave them a bit of a shock."

Mr Agnew said he saw rescue teams on islands about 10km away and tried to use the flash on his camera to get their attention

"I started to think ... I might die of dehydration. I did try to look for some water," he said.

"It was going to use a lot of energy, so I just decided to calm down and just relax."

Sen-Constable Jason Daines, of Esperance police, said Mr Agnew was extremely lucky to have escaped and he warned other divers to reconsider solo expeditions.

"He was very lucky," Sen-Constable Daines said. "He was in good health. Basically he was exhausted and a bit cold."

Mr Agnew was in Esperance Hospital under observation yesterday.

Source: http://www.perthnow.com.au