30. Deep Bay, Saskatchewan, Canada
This crater consists of a near-circular bay, about 5 kilometers wide and 220 meters deep, in the otherwise shallow Reindeer Lake. Such deep circular lakes are unusual in this region, which is dominated by the shallow gouging of glacial erosion. The circular shoreline, at a diameter of 11 kilometers, is partially surrounded by a ridge with heights to 100 meters above the lake surface. The diameter of this ridge, ~13 kilometers, is likely the outer rim of the impact structure. The structure was formed in Precambrian metamorphic crystalline rocks with a conspicuous northwest-trending fabric. Although not obvious from the surface, Deep Bay is a complex impact structure with a low, totally submerged central uplift. Samples obtained in the 1960s from drilling into the central structure revealed shocked and fractured metamorphic rocks flanked by deposits of allochthonous, mixed breccias.
Space shuttle image STS59-L08-63.