An Eastern Shore couple may have videotape proof that "Chessie," the legendary Chesapeake Bay creature that has been as elusive as the Loch Ness Monster, really does exist after all.

Robert Frew, his wife Karen and some guests were at the Frews' home on Love Point overlooking the Bay on Memorial Day, when they saw a 30-foot-long, serpent-like creature swim by. Frew first watched it through binoculars, then used his videotape camera to film it for about four minutes.

Frew is not sure how to identify the creature, but he is sure it's a stranger to the Chesapeake Bay. "Our conclusions are, number one, it's big, and number two, it sure as hell doesn't belong here," Frew told the Associated Press yesterday.

Karen Frew said she thought the creature might be "Chessie," a sea-monster sort of creature said to have been sighted a number of times in the bay over the last several decades. Until now, however, there was no more reason to think "Chessie" exists than "Nessie."

"Chessie is part of the Maryland folklore," Mrs. Frew said. "It probably was first sighted about 50 years ago, and other people have reported seeing it since. What we saw is not a run-of-the mill animal. I'd say it's similar to the Loch Ness Monster."

Spokesmen for the Enigma Project, a Baltimore-based group that investigates claims of "paranormal" occurrences, said yesterday that the organization has examined the videotape and pronounced it genuine.

"I've heard reports of these sightings--unsubstantiated--back to the 1930s," said one of the group's founders, Mike Frizzell. "Up to this point," he said, "it's been a myth."

George Zug, an official of the Smithsonian Institution who has studied photographs purportedly of Scotland's Loch Ness Monster, said he and other museum experts on sea life will examine the Frews' videotape next month.

Zug, chairman of the Smithsonian's department of vertebrate zoology, said the largest water snakes and eels common to the bay usually grow no longer than about four feet.

According to Frew, however, the creature he videotaped was eight or nine times that long. "I would say 30 to 35 feet would be about right." In girth, he said, "it's about the size of a good-sized person's thigh"--about 10 inches in diameter.

"My mind says it's a snake," Frew said, but the shape of its head--"a little more round than a football"--makes him doubt that hypothesis.

Asked what other traits the creature displayed, Frew said with a laugh: "It seemingly doesn't eat people, because it swam within 50 feet of them."

On the tape's soundtrack, Frew, his wife and two friends are heard shouting to a group of swimmers that the creature was nearing. The creature dived and then re-appeared beyond them, Frew said. "If they'd seen it at eye level, there would have been mass panic," he said.

According to Frew, the creature appeared in three- to five-foot-deep bay waters just off his property in the calmest conditions. "That day there wasn't a ripple." He said he used a zoom lens and filmed the creature from about 200 feet as it repeatedly broke the surface.

"The first time up, we saw its head and about four feet back . . . the next time about 12 feet, the next time about 20," he said, adding that more of the animal appeared to be beneath the water. The creature appeared to have humps along its back, he said.

Frew, a businessman who was trained in wildlife management at the University of Maine, said he and his family have seen sea turtles, sharks, otters and other animals in the bay, but never anything like the creature.

He said the Enigma Project officials were skeptical when he first told them about the sighting.

Bob Lazzara, co-founder of the group with Frizzell, said he and a video engineer examined Frew's tape, "to make absolutely sure it hadn't been subjected to some sort of studio effects."

"When we showed it in very slow motion, it wasn't just the appearance of the snake--I use that term because it seems to fit--it was the motion of it as it moved through the water," Lazarra said. "Whatever it is on the tape is alive. There's not someone under the water pulling it along. There's not some line tied to it and someone pulling it. It's alive."

"Now," Lazarra said, "we take the film, which we know is genuine, to marine life experts."

The Smithsonian's Zug said he hopes to assemble a marine mammalogist and a specialist in fish to examine the tape at the museum next month. No date has been set.

Lazzara said others invited to the viewing include a regional fisheries biologist, a Maryland Wildlife Federation official and scientists from the National Aquarium in Baltimore.

None is speculating about what the creature is, Lazzara said, describing their attitude as "baffled enthusiasm."