Anhumas Abyss (Abismo Anhumas)

The Anhumas Abyss (Abismo Anhumas) is a cave with a lake at the bottom, 72 meters below the surface. The entrance is a crack in the ground on a farm 23 km from Bonito, and the only way to reach the water is to descend through open space, strapped into a rappel harness. Down below, limestone cones up to 20 meters tall rise from the lake floor, and the water is clear enough to see them from the surface. It is Bonito’s most expensive tour, its most restricted, and the one most people describe as the high point of their trip.

What the tour is like

Everything starts the day before. Check-in at the attraction’s office in the center of Bonito is mandatory: you fill in a liability waiver and a medical form, try on the wetsuit and harness and do a short descent on a test platform. That is when your time for the next day is set. No check-in, no descent.

On the day, the group is small. At the mouth of the abyss each person is clipped into the motorized rappel system, which controls the speed of both descent and ascent. There is no physical effort and no rope skills needed: you sit, let go with your hands and go down. The descent is slow and, from a certain point, the cave opens up and the lake appears below. That stretch is what unnerves people with a fear of heights, and what made the place famous.

At the bottom there is a floating dock. From there the options split:

• Sightseeing: a small-boat ride across the lake, without entering the water, then back up.
• Snorkeling: with wetsuit, vest and mask, the group floats over the limestone cones while the guide points out the formations. The water is around 18 °C (64 °F).
• Scuba diving: for certified divers or a discovery dive with an instructor; you go down among the cones to about 20 meters.

The ascent is on the same cable. Between arriving at the farm and leaving, allow 3 to 4 hours.

Rules and restrictions

This is the tour with the most requirements in the region: medical form, minimum and maximum weight limits because of the equipment, restrictions for pregnant women and people with heart or respiratory conditions, and a minimum age that varies by option. The numbers change fairly often and we do not repeat them here to avoid misleading you; the agency confirms the current rules when you book. As in any water in Bonito, sunscreen and insect repellent cannot be on your skin when you snorkel, and you do not touch the formations.

Best season

The cave is sheltered from rain and the lake water is stable, but heavy rain can cancel the descent for safety reasons at the mouth of the abyss. In the dry season, May to September, the risk of cancellation is lower. Visibility inside the cave is not affected by the rainy season the way the rivers are. See our article on the best time to visit Bonito.

Price

The reference price, in Brazilian reais (BRL), is in the info box on this page with the date it was checked, and runs from sightseeing (the cheapest) to scuba diving (the most expensive). The price includes equipment, guide and insurance; it does not include transport. Tickets are bought through a licensed agency at the same price everywhere, under Bonito’s single-voucher system. The Abyss usually costs two to five times a regular river snorkel.

Is it worth it?

It depends on budget and profile. For travelers chasing adventure with days to spare, it is the most memorable tour in Bonito and has no parallel in Brazil. For those with two or three days and a tight budget, the money goes further on two or three river snorkels. A middle ground is the sightseeing option, which keeps the rappel and the boat ride at about 60% of the price of the snorkel.

Because it is on the same road as the Blue Lake Cave, many people do both on the same day. If you want another underground-water experience without the rappel, look at Lagoa Misteriosa, in Jardim. See how the Abyss fits into the 4-day itinerary and the other options in adventure tours in Bonito.