Three hours of walking through the Atlantic forest, with the humidity rising from the 36,000 hectares of the Ilha Grande State Park, and then suddenly the vegetation opens up to a small sheltered bay that seems not to belong to the present time. No kiosks, no tourist pier, no background music. Just the sound of the waves entering the cove and, at night, something difficult to describe: the water glowing with its own light, due to the bioluminescent phytoplankton that inhabits these protected waters.
Ilha Grande is located in the state of Rio de Janeiro, about 150 kilometers from the capital, accessible by ferry from Angra dos Reis or Mangaratiba. The island measures about 193 square kilometers and has remained largely unspoiled thanks to a particular history: for decades it housed first a maximum-security prison, then a penal colony, structures that were demolished in the 1990s. That difficult history has paradoxically preserved the forest and discouraged building development, making the island today one of the best-preserved areas of the Brazilian Atlantic Forest.
The path that few travel all the way
The trail that leads to the cove on the western part of the island starts from the village of Abraão, the only inhabited center of significant size on Ilha Grande. The path is not marked with elaborate tourist signs and requires adequate physical preparation: about three hours of walking on uneven terrain, with uphill sections and crossings of small streams. The surrounding forest is dense, with trees exceeding twenty meters in height and a shrub layer that filters the light until it becomes green and diffused even in the central hours of the day.
Along the way, very few people are encountered. A few local fishermen who know every turn of the trail by heart, rarely other hikers. The Brazilian Atlantic forest is one of the ecosystems richest in biodiversity on the planet, and this stretch is a concrete example of it: howler monkeys can be heard before being seen, toucans cross the treetops, and the understory hosts vegetation that changes at every bend of the trail.
The bay and the phenomenon of bioluminescence
Reaching the bay after hours of walking creates a real sense of disorientation. The water is still, protected by the natural shape of the coast, and the sandy bottom is visible even at considerable depths. During the day, local fishermen dock their small boats here, unload their catch, and repair their nets. There is no organized tourist service: no canoe rentals, no bar.
At night, the phenomenon that makes this place extraordinary becomes visible. Movement in the water — a hand submerged, the passage of a fish, a stone thrown from the shore — produces flashes of bluish-green light. These are unicellular organisms, mainly bioluminescent dinoflagellates, that react to mechanical disturbance by producing light. The phenomenon is more intense on moonless nights, when total darkness makes every movement in the water a small luminous explosion. It is not rare in protected tropical waters with low circulation, but here the concentration and isolation of the place make it a uniquely intense experience.
How to sensibly organize the visit
Those who want to reach this cove must plan carefully. Leaving from Abraão in the early morning, ideally no later than seven, allows you to arrive at the bay during the central hours of the day, rest, and wait for the sunset and then darkness to observe the bioluminescence without having to face the return trail at night. Bringing enough water is essential: at least two liters per person, considering the heat and humidity of the forest. There are no supply points along the way.
It is advisable to inquire with the residents of Abraão about the conditions of the trail before departing: tropical rains can make it slippery and in some sections difficult to follow. Some local fishermen know the route and occasionally accompany visitors, but this is not an organized service. The months between April and September, with less rainfall compared to the southern summer, offer generally better conditions for trekking, although the forest always maintains high humidity.
Ilha Grande beyond the trail
The village of Abraão, where the life of the island is concentrated, has no roads accessible by cars: motor vehicles are prohibited on Ilha Grande, and this significantly contributes to the silence that characterizes the island. The local pousada, the small trattorias along the waterfront, the morning fish market: everything operates at a different pace than any organized tourist center. The island welcomes visitors, but it has not transformed for them.
The Ilha Grande State Park was established in 1971 and includes almost the entire surface of the island. Together with other protected areas of the green coast of the state of Rio de Janeiro, it is part of a conservation system that has allowed the Atlantic Forest to survive in an otherwise heavily urbanized region. Walking for three hours in this forest and arriving at water that glows in the dark is, after all, the direct result of decades of environmental protection.
