The Aquário Natural complex is justifiably Bonito’s next most popular attraction. Located at the river’s source, 7km from town, the Aquário itself is a small sanctuary with water so clear and full of fish that the experience is like looking into an aquarium – something you can take advantage of by a ride in one of the glass-bottomed boats. In fact, visitors are encouraged to put on a floating jacket, mask and snorkel, and get into the water with the 35 or so species of fish, mainly dourado and 35cm piripitanga fishes – a tickling experience with no danger from piranhas who never swim this far upriver. The sanctuary is accessible by a path from the reception through a swamp and mata nature reserve, the Parque Ecológico Bahia Bonita, replete with wildlife, including white-collared peccaries, agouti and the majestic caramugeiro snail hawk. From the Aquário, the Bahia Bonita, a kilometre-long stretch of river, runs down to meet the Rio Formoso, where there’s a death-slide (a pulley and rope system for exciting splashdowns into the river), and trampoline-based river fun.
The Aquário Natural is only one of several snorkelling locations in the area, though it has by far the most developed infrastructure. If you’re on a tight budget, the nearby Pousada Bacuri (R$7 admission), 500m from the Aquário Natural, has a stretch of river all of its own, with dourado fish, four small waterfalls and a small forest. Tour companies also offer snorkelling trips to the Rio Sucuri (R$70 half day), and the Rio da Prata (R$140 full day). One of the best local scuba sites is the Gruta do Mimosa (R$250 full day); a trip here requires both a guide and permit, best obtained through either the Pousada Olho d’Agua travel agency or Ygarapé Tours.