Sanilac Arch

Sanilac Arch is a tunnel-like opening that pierces the southern abutment near the base of Arch Rock, which rests on a limestone breccia promontory nearly 150 feet above Lake Huron. Both arches were formed about 4,000 years ago by wave action of ancient Lake Nipissing. Once called Maiden Arch, the smaller opening was renamed Sannillac Arch in 1913 after the Wyandot leader Sannillac, and its name was eventually shortened to Sanilac Arch. Visitors once walked through it from the lakeshore, while more agile explorers approached from above along a treacherous pathway directly beneath Arch Rock. Debris from the disintegrating cliffside slowly filled the lower arch, and access is no longer permitted.

Mackinac Island, Michigan · United States