Bonito is located amid the Serra da Bodoquena, a hilly region with rocky limestone landscapes rife with strangely shaped outcrops and well over 100 caverns. Dark and humid, many contain of these grottoes feature ceilings and walls decorated with strange and fantastical stalactites and stalagmites.
Accompanied by a guide, the caves can be explored on foot, or in some cases, by rappelling down into their darkest depths. Tucked away in the large caverns are underground pools and even lagoons that, when illuminated by the sun, are transformed into shining pools of blue. Such startling colors are due to the purity of the water, which also ensures high visibility and makes it possible to snorkel and dive deep beneath the surface.
Abismo de Anhumas
Bonito’s most celebrated attraction, this narrow abyss begins as a small crack in the earth and opens up into one of the largest underground caverns in Brazil. After descending 236 feet (72 meters) by rappel with a guide, you can snorkel or dive in the seemingly bottomless lagoon where visibility is up to 98 feet (30 meters). The atmosphere is further enhanced by the arresting ensemble of stalactites and stalagmites.
Gruta do Lago Azul
This large cave, believed to date back 10 million years, showcases a seemingly bottomless underground lake that, when touched by the sun’s rays, radiates an iridescent blue (an occurrence that is most intense in December and early January, in the morning). The guided descent to the bottom is via a precarious staircase of 294 steps.
Another bottomless blue lake, this 'mysterious' underwater lagoon lives up to its name. Outfitted with snorkeling or diving gear, you can plunge into this clear pool, located at the bottom of a 246-foot (75-meter) sinkhole, and swim amidst a marine-scape of fallen tree trunks and dazzling fish. Between April and October, you can see as far down as about 164 feet (50 meters).
Grutas de São Miguel
Dating back to pre-Cambrian times, this complex of connecting caverns is located within the Reserva Natural Parque Vale do Anhumas. Stretching for more than 885 feet (270 meters), the eerie underground cavities are composed of limestone that, over the span of 650 million years, has been sculpted into bizarre forms and shapes. During the 90-minute guided walk, you’ll encounter stalactites, stalagmites, and travertines galore, plus bats and perhaps a resident owl.