A mile-long stretch of tumbled rock that runs from Commercial Street to the tip of the Cape, Provincetown Causeway is one of the best walks around, and the views from the breakers are breathtaking. Be sure to check the tide schedule and wear appropriate shoes - some of the rocks are on a challenging slant - and remember the journey is more difficult than it looks at first. If you choose to go all the way to the lighthouse at Herring Cove and back, it will take about three hours, so take sunscreen and water.