Natural 'inland lakes' lakes with summertime tempertures more suitable for water sports than Superior such as Lake Vermillion abound in those nearby areas of northeasten Minnesota. Cabins, lodges, and resorts of all flavors can be found. The South Shore of Lake Superior has more sandy beaches than the north but except at very protected locations is still generally too cold for most swimmers. Somewhat farther afield are the National Parks of Voyageurs near International Falls and Crane Lake and Isle Royale reachable by boat from Grand Portage, MN or from the upper peninsula of Michigan and the St. Croix National Scenic Riverway along the border between Minnesota and Wisconsin.
Thunder Bay is an easy destination just across the border to Canada.
Many other detailed links to outfitting and other detailed information about Minnesota outdoor activities are available. Lake Superior dominates air temperatures at points close to the shore. Because the lake surface is typically in the 50s but can be in the 40s in mid-summer, it can be quite chilly on the beaches or out on the lake . Historically temperature has ranged from 32 to 97 in August. Duluth averages just a couple of days a year greater or equal to 90 with less than 1 in August.