<Tr> <Th> Surface elevation </Th> <Td> 601.71 ft (183 m) (2013 average) </Td> </Tr> <Tr> <Th> Islands </Th> <Td> Isle Royale, Apostle Islands, Michipicoten Island, Slate Islands </Td> </Tr> <Tr> <Th> Settlements </Th> <Td> Thunder Bay, Ontario Duluth, Minnesota Sault Ste . Marie, Ontario Marquette, Michigan Superior, Wisconsin Sault Ste . Marie, Michigan </Td> </Tr> <Tr> <Td_colspan="2"> Shore length is not a well - defined measure . </Td> </Tr>

What's at the bottom of lake superior