Gulf of Mexico numerous bays and smaller inlets. A number of rivers empty into the gulf, most notably the Mississippi River and Rio Grande in the northern gulf, and the Grijalva and Usumacinta rivers in the southern gulf. The land that forms the gulf's coast, including many long, narrow barrier islands, is almost uniformly low-lying and is characterized by marshes and swamps as well as stretches of sandy beach. The Gulf of Mexico is an excellent example of a passive margin. The continental shelf is quite wide at most points along the coast, most notably at the Florida and Yucatán Peninsulas. The shelf
Gulf of Mexico of Deutsche Schiff- und Maschinenbau AG, Deschimag) at Wesermünde (modern Bremerhaven) as yard number 705, launched on November 1, 1941 and commissioned on March 23, 1942 under the command of "Oberleutnant zur See" Hans-Günther Kuhlmann. After training with the 4th U-boat Flotilla, "U-166" was transferred to the 10th U-boat Flotilla for front-line service on June 1, 1942. The U-boat sailed on only two war patrols and sank four ships totalling . She was sunk on July 30, 1942 in Gulf of Mexico. In 2001 the wreck of "U-166" was found in 5,000 feet (1,500 m) of water, less than two