AAA Editor Notes
Interstate State Park entry is off US 8 (St. Croix Trail) via Milltown Rd. to 307 Milltown Rd. The park is noted for bluffs and rock formations along the St. Croix River and especially for its glacial potholes, geological features formed in the bedrock by the action of rushing water. There are more glacial potholes within a small area here than anywhere else in the world.
The self-guiding Glacial Pothole Trail begins at the park visitor center. Interpretive signs point out various potholes, including the Bottomless Pit—with a depth of more than 60 feet, the world's deepest explored glacial pothole—and the Unexplored Pothole, the park's widest. The River Trail starts near the visitor center and winds through the bluffs high above the river; a mile and a quarter one way, it is rugged in sections. The self-guiding Railroad and Sandstone Bluffs trails offer scenic views of towering basalt rock cliffs.
Rock climbing is permitted in designated areas with a permit.
Pets on leash are allowed. Recreational activities are permitted. Camping is permitted. Picnicking is permitted. Food is available. Time: Allow 1 hour minimum.