Point Reyes Crater
Wait for low tide and then head to this natural amphitheater with a built-in skylight. The hike down can be treacherous so wear sturdy shoes and protective clothing over your bathing suit. The beach is a splendid paradise - framed by high cliffs with strange, vertical rivulets formed by erosion over eons. Head further down the beach and you'll reach a small waterfall. Make sure you have enough time to make your way back to high ground - you don't want to get trapped by the rising tide!