With one million acres of rugged northwestern Montana wilderness to explore, a trip to Glacier National Park could fill up an entire summer and more. But let's just take one day and virtually visit Grinnell Lake. A 7-mile loop trail, a relatively easy one in this mountain wilderness, takes you to the shores of the lake turned emerald green by glacial silt. Grinnell Lake—as well as Mount Grinnell and Grinnell Glacier—is named for the naturalist George Bird Grinnell. For two decades, he lobbied for federal protection of these lands, and on May 11, 1910, the 'Crown of the Continent,' as Grinnell dubbed the area, became the nation's 10th national park.