A Lake at the Edge of the World

The name "El Cusi" is deeply rooted in this corner of Bolivia. The government decree that created the ANMI San Matías in 1997 lists "estancia Cusis" as one of the boundary points of the protected area, and a neighbouring swamp — Pantano del Cusi — carries the same local designation. Together they mark a small cluster of places in the cattle-ranching hinterland where water gathers and wildlife moves freely.↗↗

There is no road, no lodge, and no signpost here. The nearest recorded neighbours are working estancias — Quo Vadis, San Agustín, La Barraca — and the town of San Matías itself lies well over 50 kilometres to the northeast. The area's population within any reasonable radius is effectively zero. What exists instead is open water, grassland, flooded palm savanna, and the seasonal rhythm of the Pantanal.↗↗

Ecological Setting

Laguna El Cusi lies within the San Matías Integrated Management Natural Area, Bolivia's second-largest protected area at nearly three million hectares. This enormous reserve spans the junction of three great South American ecoregions — the Chiquitano Dry Forest, the Cerrado savanna, and the Pantanal floodable grasslands — making it one of the continent's most biodiverse wildernesses.↗↗

The wetland mosaic that characterises this zone — called locally by terms like curichón (seasonally flooded grassland), camotal (water-lily meadow), and arrocillar (wild-rice marsh) — creates critical habitat for species found in few other places on Earth. Yacaré caimans bask on the banks, giant otters patrol the deeper channels, capybaras gather in family groups, and the blue hyacinth macaw — the region's emblematic species — nests in Copernicia palm groves nearby. With 310 bird species recorded in the broader ANMI, any pool of standing water attracts life.↗↗

The lake is also a fishing water. FishBrain lists it as a spot for anglers in Santa Cruz, though no catches are logged — a telling sign of how rarely anyone makes the journey. The Pantanal's fish fauna is rich, with 128 species registered in the broader reserve, including large catfish.

Getting There and What to Expect

Laguna El Cusi is not a tourist destination in any conventional sense. It is a point on the map that rewards those who are already deep in the Bolivian Pantanal with an operator, four-wheel drive, and time to spare. The gateway towns for this region are San Matías and Puerto Suárez, both reached from Santa Cruz de la Sierra by a long road journey through the Chiquitanía (passing San José de Chiquitos, Roboré, and El Carmen) or by daily flight or train to Puerto Suárez.↗↗

The dry season (roughly May to October) is the only realistic window for overland access. Roads become passable, wildlife concentrates around remaining water sources, and mosquito pressure drops. During the rainy season (November to April), much of the landscape floods and movement on the ground becomes extremely difficult.↗↗

There are no visitor facilities at or near the lake. Accommodation, food, and guided access in the broader San Matías ANMI require arrangements with local operators or conservation organisations with field presence. The SERNAP office in San Matías can provide information on entry requirements and current conditions.

Why It Matters to the Explorer

For most travelers, Bolivia's Pantanal will be experienced from the more accessible margins — Lake Cáceres near Puerto Suárez, the road to San Matías, or the Otuquis park entrance. Laguna El Cusi belongs to the deeper interior: the vast, roadless, wildlife-rich wetland that most visitors will only glimpse from a distance. It represents what the Bolivian Pantanal is — immense, quiet, and fundamentally wild.↗↗

The area's isolation is also a conservation asset. San Matías functions as a corridor linking Bolivia's Pantanal to Brazil's Pantanal Matogrossense National Park just across the border, ensuring large mammals like jaguars and giant anteaters have the territory they need. Every untouched lagoon in this system contributes to that ecological integrity.↗↗

Practical Tips

Visit only during the dry season (May to October), when overland travel is feasible and wildlife is concentrated.↗

Arrange access through a local operator with field presence in the San Matías ANMI; independent travel into the interior is logistically impractical.↗

Bring insect repellent, sun protection, binoculars, and a telephoto lens — the open wetland landscape rewards patient wildlife observation.↗

Check with the SERNAP office in San Matías for current entry requirements, fees, and road conditions before attempting any journey into the reserve interior.↗

A four-wheel-drive vehicle is essential for any road travel within the ANMI.↗