WThe St. Marys River, sometimes written as the St. Mary's River, drains Lake Superior, starting at the end of Whitefish Bay and flowing 74.5 miles (119.9 km) southeast into Lake Huron, with a fall of 23 feet (7.0 m). For its entire length it is an international border, separating Michigan in the United States from Ontario, Canada.
WThe Gros Cap Reefs Light is a lighthouse located at the entrance to St. Mary's River from Whitefish Bay of Lake Superior. The light was completed in 1953 and replaced a lightship stationed there since 1923. The lighthouse, owned by the Canadian Coast Guard, is located on the southwest edge of the Gros Cap Reef.
WThe Saint Marys Falls Hydropower Plant is an 18-MW hydroelectric generating plant located in Sault Ste. Marie, Michigan. It extracts water from the St. Marys River under the supervision of the Army Corps of Engineers, and the power is taken up and distributed by the Cloverland Electric Cooperative, a rural utility that serves the Soo area.
WSault Ste. Marie Bridge Company is a subsidiary of the Wisconsin Central Ltd. It operates a railroad bridge over the St. Marys River between Sault Ste. Marie, Michigan and Sault Ste. Marie, Ontario.
WThe Sault Ste. Marie Canal is a National Historic Site in Sault Ste. Marie, Ontario, and is part of the national park system, managed by Parks Canada. It includes a lock to bypass the rapids on the St. Marys River.
WThe Sault Ste. Marie International Bridge spans the St. Marys River between the United States and Canada connecting the twin cities of Sault Ste. Marie, Michigan and Sault Ste. Marie, Ontario. The bridge is operated by the International Bridge Administration under the direction of the Sault Ste. Marie Bridge Authority, a bi-national governing body consisting of four directors appointed by the Governor of Michigan and four appointed by the Canadian government-owned Federal Bridge Corporation.
WThe Sault Ste. Marie Railroad Bridge was originally built in 1887. It runs parallel to the Sault Ste. Marie International Bridge. It has nine Camelback spans and carries a single line of track.
WThe Soo Locks are a set of parallel locks, operated and maintained by the United States Army Corps of Engineers, Detroit District, which enable ships to travel between Lake Superior and the lower Great Lakes. They are located on the St. Marys River between Lake Superior and Lake Huron, between the Upper Peninsula of the US state of Michigan and the Canadian province of Ontario. They bypass the rapids of the river, where the water falls 21 feet (6.4 m). The locks pass an average of 10,000 ships per year, despite being closed during the winter from January through March, when ice shuts down shipping on the Great Lakes. The winter closure period is used to inspect and maintain the locks.