If you’ve ever wanted to walk through an underground mine tunnel system, here’s your chance…and it’s legal. Sitting abandoned for approximately 50 years, the Adventure Mine is located in Greenland Township, Ontonagon County, right at the base of the Keweenaw Peninsula. It opened for the first time in 1850 and lasted 12 years until 1862. It was purchased in 1863 and named the Adventure Copper Company, and re-named in 1898 as the Adventure Consolidated Copper Company.