St. John is dominated by the Virgin Islands National Park, with low-key development confined to the eastern and western tips of the island. Beyond Mongoose Junction and other low-key, upscale shopping spots in the louche port of Cruz Bay lies a largely undisturbed tropical paradise.
But if 'National Park' makes you think bird-watching and hiking boots, bear in mind it also covers some of the Caribbean's best beaches, especially along the island's north shore. None of them are particularly over-run, but if you want even more privacy, head to the more rugged south shore. Just about anywhere along the coast will provide excellent snorkeling opportunities.