Book excerpt: This new and completely updated edition by co-authors Doris Green and Greg Brick, PhD, invites readers to consider a different angle for their next Minnesota trip. It guides travelers to the state's publicly accessible caves, former mines, and other subterranean treasures. Whether you are a sport caver, hiker, photographer, teacher, historian, or vacationer, this guide offers unique travel destinations, suggests possible study projects, and points to both widely recognized and little known underground locations. Along the way you'll learn to see Minnesota in a different light--a light cast as often by a headlamp as by a northern sky. YOU'LL FIND: - 82 sites in 23 counties - 41 new site listings - 13 museums and educational centers featuring cave and mine replicas as well as geologic exhibits - 23 sidebars highlighting Minnesota's underground history and geology--not to mention odd but true subterranean tales - Directions, precautions, and amenities for all sites listed This guide offers ideas for travelers who want an unordinary travel experience. While some sites require sure-footedness and an ability to climb steep hillsides, others are accessible even for families with young children. If you're ready for a serious trek or an easier tour beneath the surface, Minnesota Underground can the lead the way.