Ilha Grande is one of the most pristine remnants of Brazil's Atlantic rainforest, one of the richest ecosystems in the world, and a hotspot for biodiversity and conservation. The seas around the island, which are also protected, feature a unique convergence of tropical, subtropical, and temperate-zone marine life, and may be the only waters in the world where it is possible to see corals and tropical fish along with Magellanic penguins and Southern right whales (if you’re lucky!).