On a moonless January night in 2003, Olivier de Kersauson, the French yachtsman, was racing across the Atlantic Ocean, trying to break the record for the fastest sailing voyage around the world, when his boat mysteriously came to a halt. There was no land for hundreds of miles, yet the mast rattled and the hull shuddered, as if the vessel had run aground. Kersauson turned the wheel one way, then the other; still, the gunwales shook inexplicably in the darkness. Kersauson ordered his crew, all of whom were now running up and down the deck, to investigate. Some of the crew took out spotlights and shone them on the water, as the massive trimaran-a three-hulled, hundred-and-ten-foot boat that was the largest racing machine of its kind, and was named Geronimo, for the Apache warrior-pitched in the waves.

　　Meanwhile, the first mate, Didier Ragot, descended from the deck into the cabin, opened a trapdoor in the floor, and peered through a porthole into the ocean, using a flashlight. He glimpsed something by the rudder. It was bigger than a human leg, Ragot recently told me. It was a tentacle. He looked again. It was starting to move, he recalled.

　　He beckoned Kersauson, who came down and crouched over the opening. I think its some sort of animal, Ragot said.

　　Kersauson took the flashlight, and inspected for himself. I had never seen anything like it, he told me. There were two giant tentacles right beneath us, lashing at the rudder.

　　The creature seemed to be wrapping itself around the boat, which rocked violently. The floorboards creaked, and the rudder started to bend. Then, just as the stern seemed ready to snap, everything went still. As it unhooked itself from the boat, I could see its tentacles, Ragot recalled. The whole animal must have been nearly thirty feet long.

　　The creature had glistening skin and long arms with suckers, which left impressions on the hull. It was enormous, Kersauson recalled. Ive been sailing for forty years and Ive always had an answer for everything-for hurricanes and icebergs. But I didnt have an answer for this. It was terrifying.

　　What they claimed they saw-a claim that many regarded as a tall tale-was a giant squid, an animal that has long occupied a central place in sea lore; it has been said to be larger than a whale and stronger than an elephant, with a beak that can sever steel cables. In a famous scene in 20,000 Leagues Under the Sea, Jules Verne depicts a battle between a submarine and a giant squid that is twenty-five feet long, with eight arms and blue-green eyes-a terrible monster worthy of all the legends about such creatures. More recently, Peter Benchley, in his thriller Beast, describes a giant squid that killed without need, as if Nature, in a fit of perverse malevolence, had programmed it to that end.

　　Such fictional accounts, coupled with scores of unconfirmed sightings by sailors over the years, have elevated the giant squid into the fabled realm of the fire-breathing dragon and the Loch Ness monster. Though the giant squid is no myth, the species, designated in scientific literature as Architeuthis, is so little understood that it sometimes seems like one. A fully grown giant squid is classified as the largest invertebrate on Earth, with tentacles sometimes as long as a city bus and eyes about the size of human heads. Yet no scientist has ever examined a live specimen-or seen one swimming in the sea. Researchers have studied only carcasses, which have occasionally washed ashore or floated to the surface. Other evidence of the giant squid is even more indirect: sucker marks have been spotted on the bodies of sperm whales, as if burned into them; presumably, the two creatures battle each other hundreds of feet beneath the oceans surface.

　　On a moonless January night in 2003, Olivier de Kersauson, the French yachtsman, was racing across the Atlantic Ocean, trying to break the record for the fastest sailing voyage around the world, when his boat mysteriously came to a halt. There was no land for hundreds of miles, yet the mast rattled and the hull shuddered, as if the vessel had run aground. Kersauson turned the wheel one way, then the other; still, the gunwales shook inexplicably in the darkness. Kersauson ordered his crew, all of whom were now running up and down the deck, to investigate. Some of the crew took out spotlights and shone them on the water, as the massive trimaran-a three-hulled, hundred-and-ten-foot boat that was the largest racing machine of its kind, and was named Geronimo, for the Apache warrior-pitched in the waves.

　　Meanwhile, the first mate, Didier Ragot, descended from the deck into the cabin, opened a trapdoor in the floor, and peered through a porthole into the ocean, using a flashlight. He glimpsed something by the rudder. It was bigger than a human leg, Ragot recently told me. It was a tentacle. He looked again. It was starting to move, he recalled.

　　He beckoned Kersauson, who came down and crouched over the opening. I think its some sort of animal, Ragot said.

　　Kersauson took the flashlight, and inspected for himself. I had never seen anything like it, he told me. There were two giant tentacles right beneath us, lashing at the rudder.

　　The creature seemed to be wrapping itself around the boat, which rocked violently. The floorboards creaked, and the rudder started to bend. Then, just as the stern seemed ready to snap, everything went still. As it unhooked itself from the boat, I could see its tentacles, Ragot recalled. The whole animal must have been nearly thirty feet long.

　　The creature had glistening skin and long arms with suckers, which left impressions on the hull. It was enormous, Kersauson recalled. Ive been sailing for forty years and Ive always had an answer for everything-for hurricanes and icebergs. But I didnt have an answer for this. It was terrifying.

　　What they claimed they saw-a claim that many regarded as a tall tale-was a giant squid, an animal that has long occupied a central place in sea lore; it has been said to be larger than a whale and stronger than an elephant, with a beak that can sever steel cables. In a famous scene in 20,000 Leagues Under the Sea, Jules Verne depicts a battle between a submarine and a giant squid that is twenty-five feet long, with eight arms and blue-green eyes-a terrible monster worthy of all the legends about such creatures. More recently, Peter Benchley, in his thriller Beast, describes a giant squid that killed without need, as if Nature, in a fit of perverse malevolence, had programmed it to that end.

　　Such fictional accounts, coupled with scores of unconfirmed sightings by sailors over the years, have elevated the giant squid into the fabled realm of the fire-breathing dragon and the Loch Ness monster. Though the giant squid is no myth, the species, designated in scientific literature as Architeuthis, is so little understood that it sometimes seems like one. A fully grown giant squid is classified as the largest invertebrate on Earth, with tentacles sometimes as long as a city bus and eyes about the size of human heads. Yet no scientist has ever examined a live specimen-or seen one swimming in the sea. Researchers have studied only carcasses, which have occasionally washed ashore or floated to the surface. Other evidence of the giant squid is even more indirect: sucker marks have been spotted on the bodies of sperm whales, as if burned into them; presumably, the two creatures battle each other hundreds of feet beneath the oceans surface.