The seashore’s visitor middle in Eastham offers a complete overview of the world, and connects to a quantity of mountaineering trails. The crown jewel of mountaineering on the Cape, nonetheless, is the Great Island Trail, a virtually seven-mile hike along the National Seashore in Wellfleet. One of the best raw bars on the Cape is inside a no-frills, buoy-clad shack on the shores of Sesuit Harbor. Order oysters, steamers, and mussels from the bar, then seize a lobster roll — the kind that is lovingly placed in those red-and-white paper boats — from the primary restaurant. Enjoy it all at …