Eyes wide, the couple from Detroit stood speechless, watching raw-red lava flow into the blue Pacific along the coast of Hawaii's Big Island, a spectacle that has become a regular tourist attraction for cruise ships.

"Eat your heart out, Cecil B. De Mille," the husband said, peering at the erupting volcano through binoculars. "This is better than the movies. This is real!"It happens around midnight every Tuesday when the 682-foot S.S. Constitution and her sister ship, the S.S. Independence, pass about a half-mile off the black lava coast where Kilauea is putting on one of the greatest natural shows on Earth.

The volcano, which erupted into life in 1983 on the east rift at the 2,500-foot level, shows no sign of slowing down. The lava flow thus far has destroyed nearly 200 houses and added an area almost as big as San Francisco to the island.

"If you don't have a volcano in your backyard, and most of us don't, then you won't want to miss this," ship's Capt. Donald D. Bennett of Sun City, Calif., tells 600 passengers at the first night briefing aboard the S.S. Constitution.

The volcano is an unadvertised highlight of the cruise because nobody, not even the Hawaii Visitors Bureau, dares predict how big the lava flow will be. Or when it will stop. That's up to Madame Pele, the legendary Hawaiian goddess of fire.

The S.S. Constititution and S.S. Independence, the only two American-flag ships cruising Hawaii's waters, now schedule their weekly 932-mile voyages around the seven inhabited islands of Hawaii so that they pass in the night off the Big Island's volcano coast.

It may be the best free show in Hawaii.

"You become an eyewitness to a living, breathing history, science and geography class," said Christiane Walsh, director of passenger services. "There's fire in the sky, the land and the sea."

While the ship's daily "Tradewinds" poop sheet offers a caveat - "Sighting of the lava flow depends on the activity of our volcano" - everyone aboard gets stoked up for the big moment.

Bartenders pour a firey red rum-based "volcano" cocktail as the featured drink of the evening. The cruise director hosts an 11:05 p.m. "Hang Loose" pajama party on the upper deck as the ship cruises from Hilo to Kailua-Kona along the Big Island's Puna coast where the lava meets the sea.

And the ship's purser provides a "volcano wakeup" for sleepy-heads.

Stateroom phones start ringing around midnight, and nearly everyone gets up to go out on the starboard decks to watch as the captain slows the ship down to volcano-watch speed of 2 knots about a half-mile offshore.

Hundreds of pajama-clad passengers who press against the starboard rail to see the live volcano erupt in tropical darkness are seldom disappointed.

"I can't believe I'm seeing this," a Chicago housewife told her video camera as she zoomed in and tried to record all the action. "It's ... it's unforgettable."

Near its 4,093-foot summit, Kilauea gave off a big, bright red glow against the night sky. The earth itself is on fire. Rivers of red molten rock runs down the slopes of the crater and cascades into the cool salt water. Steamy clouds smelling like rotten eggs leach into the night sky.

"You can see it and you smell it," said Rory Paikai, 20, a new shipboard waiter from Honolulu getting his first close-up Kilauea's majesty.

Flashbulbs pop as passengers take countless rolls of pictures, then snap shots of each other with the volcano in the background. The official ship's photographer took pictures of everyone taking pictures.

"My grandchildren won't believe it," said Thelma Duke of Bakersfield, Calif., as the natural fireworks blazed in the night.

All of the ship's 320-member crew have seen the volcano at least once, but they all turn out to see it, again and again. "It's different every week," said Capt. Bennett, who stepped out of the bridge at midnight in his dress whites to see the show.

"You never know what to expect," he said.

"It's one of the most spectacular sights in Hawaii," said Eugene LeBeaux, a Los Angeles-based trombone player with the ship's orchestra.

The volcano may be an even bigger attraction than Alaska's humpback whales who migrate to Hawaii in December and surface off Maui to the delight of cruise ship passengers.

"Everyone knows what a whale looks like," said Rose Rice of Honolulu who runs the ship's beauty salon, "but not many people get to see a volcano, especially from the sea."

A week's cruise costs between $1,000 and $3,000, depending on accommodations, and while nobody at the San Francisco-based American Hawaii Cruises keeps statistics on how many passengers the volcano attracts, it has a big following.

Doris Owen of Houston has been back every year for the last three years, mostly to see the volcano. "It's the main reason I booked the cruise," she said, "that and the food and the dancing."

Owen thought the show was better last year: "It was more out of control," she said, "but who's complaining?"