The Sault Ste. Marie Locks are a set of locks located on the St. Marys River in Sault Ste. Marie, Michigan. They facilitate the passage of ships between Lake Superior and Lake Huron, overcoming a height difference of about 21 feet. The locks are crucial for maritime trade, allowing large vessels to navigate this important waterway. Constructed in the early 20th century, the locks are among the busiest in the world. They are operated by the U.S. Army Corps of Engineers and can accommodate various types of vessels, including cargo ships and recreational boats. The locks play a vital role in the economy of the region.