As Waikiki beachgoers greased up with tanning oil or sunblock yesterday, some water enthusiasts found themselves speckled with a different kind of goo.

The grease, possibly from a leaking vessel, could have been driven toward the beach with the change in wind direction, said Janice Okubo, Department of Health spokeswoman.

The black, slimy balls started appearing at about 10 a.m. in the Canoes surfing spot off the Sheraton Moana Surfrider Hotel and came ashore near the Waikiki groin area. They largely disappeared by 3 p.m.

It got in surfers' hair and on their swimsuits and boards. One surfboard rental company used WD-40 to remove the tarlike substance.

Initially, the Health Department called the flotsam “;tar balls”; - remnants of oil spills that float for hundreds of miles, according to the National Oceanic and Atmospheric Administration.

Health Department investigators took samples back to the office and later decided they were grease.

The difference: Tar balls travel farther and float longer, while grease comes from a more recent event, Okubo said.

She called it more of a nuisance than a health hazard.

“;Everybody's bathing in oil right now,”; said Larry Akiyama, a surf instructor at Hawaiian Oceans who has been using the beach for more than 50 years. “;First time it's happened in Waikiki.”;

One of the balls appeared on his forehead while he was giving a surf lesson.

“;It stuck on my face,”; he said. He rubbed it off with spit and sand.

After that he warned students about the pollution, but they mostly just laughed, he said.

Dahlia Schwartz of Toronto got a spot of it on her foot while walking in the water near Moana Surfrider.

“;It was gross. It was on my blister,”; she said. A lifeguard gave her baby oil to rub it off.

The Coast Guard also investigated the floating gunk, although they did not find much, said Coast Guard Petty Officer 3rd Class Michael De Nyse.

The Coast Guard opened an independent investigation and will send samples to a lab to determine the vessel that released the oil-based substance into the water, De Nyse said. He said he did not know how long it would take to receive test results.