The Scituate sea monster: a 30-foot carcass on Mann Hill Beach that Harvard experts identified as a basking shark

Scituate sits on the Massachusetts coast, south of Boston. Its shoreline has a long memory for sea monsters. The local historical society says the town had two before 1970. The coastal historian Edward Rowe Snow recalled similar carcasses washing up at Gloucester and Plymouth in the 1700s. This is the same coast that gave the world the Gloucester sea serpent.

November 1970. A Saturday evening. An 11-foot high tide, which the Harvard Crimson called mammoth, rolled onto Mann Hill Beach in North Scituate. It left a body on the sand.

Police described it to UPI as a 30-foot sea serpent, a decomposed body weighing between 15 and 20 tons. It was coral-coloured, with a small head, a long neck and a large, finned body. It resembled a camel without teeth. "It's fantastic," said one officer.

In Kansas, the University Daily Kansan printed the wire story under the headline "Match This Loch Ness." Later accounts added two large front flippers. One visitor drove over from Franklin with friends and saw both the carcass and the head that had been removed. The head resembled that of a large dog, they wrote, with two spikes protruding from it. "They were like knitting needles."

Paul Sieswerda, salt-water aquarist at the New England Aquarium, first saw the carcass on television. It gave every indication, he said, of being a classical sea monster. Executive Director Donald De Hart sent him to the beach. He arrived to find about 250 college-age young people chanting and screaming around the body. Aquarium officials feared the next high tide might wash it away.

Sieswerda looked closely. He saw a cartilaginous skeleton. He thought of a large shark. Then he took the head. "I got a '53 Buick and I just couldn't get too much of it in."

Thousands came over Sunday night and Monday. One later account puts the number above 10,000 across three days. Souvenir hunters hacked off pieces of what was left.

Experts including Tyson Royal Roberts, Harvard's Assistant Curator of Fishes, dispelled all belief that it was a sea monster. The Harvard Crimson reported their finding on 17 November 1970. "They have definitely determined that the carcass is that of a mangled basking shark, which may have died at sea and was partially eaten by other sea life as it drifted ashore." The paper nicknamed it "Cecil the seasick sea serpent." What remained was fed to the aquarium's garbage disposal.

A rotting basking shark is a famous impostor. Oily livers and decomposition gases keep the dead animal afloat. The gill skeleton sloughs away, leaving a tiny skull on the end of a long, plesiosaur-like neck. The lower tail lobe rots off, leaving a snake-like tail, and the pectoral fins remain as flippers. Still, some who saw it maintain that the slimy cadaver was something undiscovered.

Cryptid writers, among them Brent Swancer, record the shark verdict but still list the Mann Hill carcass among plesiosaur-like strandings. It belongs to a family of carcasses later identified as basking sharks, including the Stronsay Beast of 1808 and the Zuiyo-maru of 1977. In 2024 the Harvard Museum of Natural History featured the Scituate Sea Monster in its exhibition Sea Monsters: Wonders of Nature and Imagination, as a decaying basking shark.