Lake Superior sits at the top of the Great Lakes system. It receives inflow from dozens of rivers including the Ontonagon, St. Louis, Nipigon, Pigeon, and Tahquamenon, among others. It drains east through the St. Marys River at Sault Ste. Marie into Lake Huron, continuing through the lower Great Lakes and ultimately reaching the Atlantic Ocean via the St. Lawrence River. The Ontonagon River, which enters the lake at the town of Ontonagon, is one of the larger Michigan tributaries and was historically important for copper mining transport.
Lake Superior does not fully freeze in most winters. Nearshore ice forms in protected bays and river mouths but is highly variable and can be undermined by currents and wave action. Ice fishing occurs in sheltered spots, but conditions are far less predictable than inland lakes — local knowledge is essential, and open-water areas remain dangerous all winter.