An abalone diver who disappeared off of the northern Sonoma County coast remained missing Tuesday night and the man is presumed dead, said a Sonoma County sheriff's official.

"There's no sign of him yet," said sheriff's Sgt. Ed Hoener late Tuesday afternoon. "We're basically treating this as a recovery at this point. We're presuming he's underwater still."

State park divers and sheriff's search and rescue volunteers, among others, spent the day at Fisk Mill Cove in Salt Point State Park, where the diver was last seen.

The search was hindered by thick kelp in the large-sized cove and only a 5-foot visibility, said Hoener.

Monday afternoon, the man had been in the cove looking for abalone with his wife watching from the shore.

A state park ranger in the area had checked in with her not long before he disappeared and everything at that point appeared to be fine, Hoener said.

At about 5 p.m. the woman called for help when her husband didn't come up for air.

"At some point he went down and didn't resurface. The area is thick with kelp. We don't know if that's a factor or not," Hoener said.

A search Monday night was underway until dark. It resumed early Tuesday. Low fog grounded an aerial search, but officials hoped to get a helicopter over the area Wednesday and divers back in the water.

While sheriff's officials know his identity, it was not released Tuesday.

Initial reports Monday night indicated the missing diver was believed to be a local resident. Hoener would not confirm his town of residence, saying only he was an experienced diver.

Fisk Mill Cove, south of The Sea Ranch coastal community, is popular with ab divers. "It's a good-sized cove. ... It's a beautiful place to dive," Hoener said.

You can reach Staff Writer Randi Rossmann at 521-5412 or