Dili

Scuba diving off the shores of East Timor's rugged Atauro Island is like crashing a flamboyant underwater Mardi Gras party thrown secretly by nature itself, a psychedelic tableau that makes Finding Nemo look like minimalist cinema. This little-known gem, lounging smugly just north of Dili, flaunts one of the highest concentrations of marine diversity on the globe-take that, Great Barrier Reef-and yet remains charmingly unspoiled by the usual crowds of selfie-stick wielding tourists. Arrive in the morning, preferably early enough that the fish are still nursing hangovers and the water clarity rivals your Instagram filters. A day trip from Dili is completely feasible, but book a dive shop or guide at least a few days ahead to secure your spot; expect to budget around $80-$120 USD for a couple of dives and equipment. And for Poseidon's sake, don't forget sunscreen (reef-safe, lest you incur Mother Nature's wrath), a waterproof camera, and your best Jacques Cousteau swagger. Even if the only marine life you can identify is "pretty fish" and "big scary eel thing," the sheer vibrancy and scale of the spectacle-combined with bragging rights at your next dinner party ("Oh, you've been to Bali? Cute.")-is worth every frantic fin-kick and awkward struggle into the wetsuit.