The main draw for most visitors to Caravelas is to view the incredible array of rare and colorful tropical fish that thrive in the transparent blue coastal waters protected by Parque Nacional Marinho dos Abrolhos. Abrolhos comes from the Portuguese command abre os olhos (“open your eyes”), and visitors to the archipelago will feel guilty if they so much as take time out to blink. Both Charles Darwin and Jacques Cousteau were impressed by the sheer diversity of fish, coral, sea tortoises and marine birds that make their home in this live aquarium.

From May to September, when visibility is at its best, it’s possible to see to depths of 20 meters. Between July and November, an added bonus is watching the spectacle of humpbacked whales—16 meters (33 feet) in length and 40 tons in weight—who mate and give birth in the warm waters. September and October are the best months to see them in action. July and August can be tricky since rainy weather can result in excursions being cancelled.

From Caravelas, it takes a little over two hours to reach the Abrolhos archipelago by speedboat, and 3.5 hours by catamaran. Full-day excursions, with a minimum of eight people, are offered by two main companies in Caravelas: Abrolhos Turismo (Praça Dr. Imbassaí, tel. 73/3297-1149) and Abrolhos Embarcações (Av. das Palmeiras 2, tel. 73/3297-1172), for around R$220 a day. If you have time to spare (and money to spend), both companies also offer overnight trips with accommodations on schooners. Diving and snorkeling equipment can be rented for an extra fee. Advance reservations are advised.