Arriving by sea, you'll experience the innumerable shades of blue that are the lagoon encircling Fakarava, one of the largest atolls in French Polynesia's Tuamotu Archipelago. Once you step ashore, you'll notice the beaches alternate between whitest white and palest pink sand, with a backdrop of coconut trees swaying gently in the tropical breeze. And while this pristine paradise—which counts only around 800 residents on an island 60 kilometers (37 miles) long and 21 kilometers (13 miles) wide—has a healthy tourism industry, it's also a UNESCO Biosphere Reserve. That designation means Fakarava, as well as its six neighboring atolls, are entirely protected—both onshore and in the surrounding waters. No wonder then that Fakarava is famous for its incredible snorkeling and diving. A lagoon excursion, which also spirits you to the atoll's most beautiful beach—one accessible only by boat—is a great way to complete your Seven Seas fantasy.