If you are looking for a less traveled national park/monument with high adventure potential, head to Dinosaur National Monument to raft the Green River, hike canyons, and see the Dinosaur Quarry. This is a great destination for families.
Caribou Falls is an approximately 1-mile out-and-back hike, off of MN-61 between Tettegouche and Temperance State Parks. This is a subtly marked hike, meaning that although it is just a short distance away from the scenic highway that runs along Lake Superiors shore, you just might get to enjoy this waterfall by yourself. Enjoy the peacefulness of the Caribou River along your hike to the falls.