Jenson said the victim straddled the hole for about 30 seconds, while other witnesses said the boy had said he wanted to feel the force of the spout against his chest.

"I just had time to wonder what he was doing," Jenson said. "Then some spray came up, he was smiling, kind of laughing ... it looked like he was having fun."

Then "a big wave came up and knocked him off his feet," Jenson said. "He lost his footing. It flipped him over and he fell in head first."

Lifeguards on jet-propelled watercraft, fire rescue divers, Coast Guard and Fire Department helicopters all searched the area until dark last night and had found no sign of the man.

Firefighter Todd Hugo, a rope tied around his waist, repeatedly stuck his head into the three-foot-diameter hole in the rocks to try to spot the victim.

"It narrows, but then it opens up about eight feet down, and I was trying to get a good angle," said Hugo, who was snatched out of the hole each time the waves sent a spout of water and spray 20 feet into the air.

"You could tell when it was coming in — there was a kind of humming sound," Hugo said.

Firefighters lowered a mirror into the hole in hopes of catching a glimpse of the man, and dropped water bottles and a rope carrying a bundle of rubber slippers into the cavern to see where they might emerge in the ocean 50 feet away.

Firefighter Dan Kapuniai said he had heard of the three other cases in which people had fallen into the hole, during an era in which his father, Dan Kapuniai Sr. was a firefighter.

"I called my dad as soon as we heard about this, and he said all we can do is wait for low tide and hope he washes out into the ocean," Kapuniai said.

Fire Capt. Richard Soo said three young women said they had come by bus to Sandy Beach where they met the victim for the first time that afternoon, and had walked over the rocky shelves with him to the hole.

There is a locked gate at an old stairway from the lookout down to the Blowhole, with a diamond-shaped yellow city Parks Department sign warning, "Hazardous Conditions, Do Not Go Beyond This Point." Below the warning, someone has pasted a circular sticker bearing a picture of a skull and the words, "Boneyard Reef."

"They can still get to the area from From Here to Eternity Beach on one side, and Sandys on the other," Arciero said.

Some Honolulu men, who declined to give their names, said they saw the victim from the lookout when the spout hit him. "We seen this guy and we didn't know what he was doing down there," one said. "He stood over the hole, leaning over it with his arms out, waiting for the wave. When the spout came it shot him up three feet and then he fell on the rock and slipped into the hole."

Chris Gahl of Hawai'i Kai, a Honolulu public relations man, was with his wife, Catherine, on the beach in a cove on the Honolulu side of the blow hole when some of the party came over the rocks calling for help.

One of them, Gahl said, told him the victim had said "he wanted to feel the water hit his chest."

The Gales said another witness reported the victim had walked right by them toward the hole, and that they warned him to stay away. He kept going, leaned over the hole while the witness stood speechless, and then was hit by the spout "that picked him up five feet into the air and flipped him over."

The girls walked back and forth on the lookout, often in tears, talking to officials and avoiding reporters, and then huddled in the cab of one of the fire trucks to wait for news.

"I only met him a half-hour ago," said one of the girls, her face red from crying. She was comforted by a young man wearing a T-shirt with the slogan, "Every day, death is near."