The SS Edmund Fitzgerald, a 729-foot-long ship launched on June 8, 1958, sank on November 10, 1975, in Lake Superior with 29 crew members on board. The vessel had departed Superior, Wisconsin, the previous day carrying 26,116 long tons of taconite, a type of iron ore used in steel production. During its journey, the Fitzgerald was sailing alongside the Arthur M. Anderson, another cargo ship, when both encountered a severe storm. Captain Ernest McSorley reported that the ship was taking on water and tilting before its lights disappeared from view, prompting the Coast Guard in Sault-Sainte-Marie to be alerted. No bodies were recovered from the wreck, and it is now considered a burial site. The wreck was discovered in 1976 at a depth of more than 160 meters (approximately 530 feet) in Canadian waters off the coast of Ontario. The U.S. Navy's CURV III submersible found the wreck on May 20, 1976, six months after the incident. The ship's stern, bearing the letters "Edmund Fitzgerald," was found upside down at 535 feet below the surface. The device recovered 43,000 feet of video tape and 900 photographs, which have led to various theories about the cause of the sinking. Two federal investigations were conducted after the disaster: the Coast Guard's report, published in 1977, and the National Transportation Safety Board (NTSB) report, published in 1978. The Coast Guard could not determine the cause with certainty but suggested that massive flooding of the cargo hold might have occurred due to ineffective closures of the panels under waves sweeping the deck. The NTSB report, MAR-78-03, dated 1978, attributed the wreck to the collapse of the cargo hold panels, dismissing theories about simple leaks and crew error. The Lake Carriers' Association, representing American shipowners, rejected the idea that the crew had improperly closed the panels, instead suggesting the ship struck the Six Fathom Shoal between the Caribou and Michipicoten islands before flooding through breaches in the bottom and ballast tanks. An amendment to the Ontario Heritage Act, applied in 2006, protects the wreck site with a 500-meter zone around the ship, discouraging visits and sampling. Only one object has officially been recovered from the wreck: the ship's bell, retrieved on July 4, 1995, and displayed at the Great Lakes Shipwreck Museum. The museum presents the findings of the Coast Guard, the NTSB, and the Lake Carriers' Association but does not resolve the debate over the causes of the sinking. Every November 10, the bell is rung at the museum once for each of the 29 men and then a thirtieth time for all the sailors missing on the Great Lakes. The exact depth of the wreck has been cited as 535 feet in 1976 and 530 feet in some sources, likely due to differing measurements. The wreck remains inaccessible to ordinary divers and can only be explored by remotely operated robots.