cave · Bonito, MS
Gruta do Lago Azul
A monumental cave holding a deep-blue lake at the bottom, lit by sunlight entering through the cave mouth. The descent on stone steps passes huge stalactites.
Illustrative images. The pictures in this guide are illustrations based on the real place, not photographs, and may differ from it.
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About Gruta do Lago Azul
The Gruta do Lago Azul (Blue Lake Cave) is a limestone cave with a turquoise lake at the bottom. It was found in 1924 by a Terena Indigenous man and listed by Iphan (the national heritage institute) in 1978, along with the neighboring Gruta Nossa Senhora Aparecida. Since 2001 it has been a state Natural Monument, covering about 273 hectares and managed by Imasul (the state environmental agency).
The visit is a descent of about 300 steps through the cave mouth, wearing a helmet and in small groups, always with a guide. Groups have a maximum of 15 people, and the descent follows the group's pace, with stops for the guide to explain. Down below, the lake, more than 50 meters long, fills the bottom of the chamber. The cave mouth is about 40 meters across. The color comes from the very clean water and dissolved limestone. Research divers have gone beyond 80 meters deep, and the bottom has not yet been fully mapped.
Along the way you see stalactites and stalagmites, and the guide explains how the cave formed. You do not touch the formations: the oil from your hands stops them from growing. Research in the lake has found fossils of animals extinct for more than 10,000 years, such as the giant ground sloth and the saber-toothed cat.
The visit is for viewing only: you do not go into the water. The guide is always accredited, and visits are controlled by Imasul together with the agencies. Between September and February sunlight reaches deeper through the opening and lights up the lake, the moment of most intense color.
Before you go
Practical information
How much time to set aside
About an hour, including the descent and the climb back up.
Best time
Between September and February, when the sun reaches deeper into the cave and the water looks bluer. The light is usually better in the morning.
How to get there
It is about 20 km from downtown Bonito, on a dirt road. The visit is guided and can only be booked through an accredited travel agency, with a voucher. Once booked, you can drive there in your own car.
Tip
Wear sneakers: they are required, and the steps are damp. There is a minimum age; check with your agency before booking for children.
A look at the place
Gruta do Lago Azul in pictures
These pictures are illustrations based on the real place, not photographs. They may differ from the place.
Click the picture to enlarge it.
Get your questions answered
Frequently asked questions about Gruta do Lago Azul
Can you swim in the lake?
No. The visit is for viewing only, from the trail inside the cave.
Do I need a guide?
Yes. The visit is always guided and can only be booked through an accredited travel agency, with a voucher.
Is there a minimum age?
Yes. The Imasul rule published in 2021 sets it at 6 years old or 1.30 m tall. Confirm with your agency before booking for children.
How many steps is the descent?
About 300 steps. The descent is done wearing a helmet and in small groups. Sneakers are required.
When does the lake look bluest?
Between September and February, when the sun reaches deeper through the cave mouth and lights up the water.