Its name speaks of canoes, but some may say that underground is where you can find the real action in Missouri. Why? There are over 5,500 caves tunneling beneath the state's surface, explaining one of its nicknames, the Cave State. It's also not a bad place to be in the warmer months, at the temperature stays at a cool 60 degrees Fahrenheit year-round. The most famous of these below-surface treasures is named after Samuel Clemens himself, since the spooky Mark Twain Cave (tel. 573/221-1656; www.marktwaincave.com) in Hannibal is featured in The Adventures of Tom Sawyer. A 55-minute tour will take you through narrow, winding tunnels (although it is predominately flat terrain, so it's not a terribly strenuous hike), where you can see an incredible example of Mother Nature's handiwork and hear tales of how the outlaw Jesse James used to hide out here, as did African-American slaves seeking freedom via the Underground Railroad. Another standout is Bridal Cave in Camdenton (tel. 573/346-2676; www.bridalcave.com); it got its name from the legend of an Osage Indian ceremony performed there in the 19th century, and now the cave has served as a romantic backdrop for the nuptials of nearly 2,000 brides and grooms to date. Inside, the stunning onyx formations, gigantic rock columns, and mineral deposits are of some the most unique in the state. There are, however, caves throughout the Ozarks and in other areas of the state; you can learn more about them through the National Caves Association (tel. 866/552-2837; www.cavern.com).