Often voted Bonito’s most unforgettable attraction, the Anhumas Abyss (Abismo de Anhumas) is truly an otherworldly experience. It begins when you don rappel gear and then courageously leap into a narrow crack in the earth, which subsequently widens into a vast cavern. One of the largest underground caves in Brazil, the abyss' walls are decorated with a fantastic array of stalactites and stalagmites.
A 236-foot (72-meter) plummet straight down into the cavern brings you to an underground lake where you can dive or snorkel in the transparent waters with visibility at nearly 100 feet (30 meters. After hours spent in this dim and enchanted netherworld, the trip back up to earth can come as a shock.
The abyss is located on the Fazenda Anhumas, which can be reached by following the Estrada para Campo dos Índios from Bonito for 15 miles (24 km). A appelling and snorkeling experience costs R$465, and the adventure lasts between three and four hours. Advance reservations are required, as daily visits are limited to two groups of eight participants. The guided excursion begins with an obligatory 30-minute rappel training session in Bonito.