About two hours' drive from Milwaukee is Wisconsin Dells, which takes its name from the distinctive sandstone formations in the glacial gorges of the Wisconsin River.
The city bills itself as the 'Waterpark Capital of the World', and with more than 20 indoor and outdoor parks it has a good claim to the title. Three of its parks claim the titles of the biggest waterparks in the US: Noah's Ark is the largest outdoor waterpark, with over 80 rides and attractions; Wilderness Territory is the indoor park; and Mount Olympus Water and Theme Park is the largest resort and waterpark complex.
Aside from the waterparks, there are boat tours of the dells and watersports. There are plenty of things to do in the Winsconsin Dells if you'd like to stay dry, however: golf and miniature golf, go karts, horseback riding, Timber Falls Amusement Park, Ripley's Believe It or Not Museum, live theatre and entertainment, and plenty of restaurants and shopping. The Ho-Chunk Casino is also a great place for adults to enjoy themselves.
The Wisconsin Dells are open in the winter, and in addition to the indoor waterparks and amusements, there is snowboarding, skiing, ice fishing and other winter activities.