In the heart of the Amazon Basin, Santa Rosa, a shape-shifting island, has reignited a long-standing border dispute between Peru and Colombia, underscoring the complexities of sovereignty in a dynamic river environment. The island’s ever-changing geography, driven by the Amazon River’s flow, has made it a focal point of diplomatic tensions, with both nations asserting claims over the territory and its 3,000 residents.
Santa Rosa Island lies at the tri-border junction of Peru, Colombia, and Brazil, where the Amazon River constantly reshapes the landscape. Each year, sandbanks form and disappear as the main channel carves new paths, leaving the island’s size and shape in flux. Official settlement began in the 1970s, but the land has never been stable, with residents adapting to seasonal changes—walking across dry sandbanks in low-water periods and navigating flooded streets by canoe during rains.
The lives of Santa Rosa’s inhabitants are deeply intertwined with the river’s rhythms, but recent environmental shifts have added uncertainty. Historic droughts in 2023 and 2024, as reported by Brazil’s Geological Service, caused water levels to plummet to record lows, disrupting traditional patterns. Food prices spiked, travel became arduous, and some families temporarily relocated to stay near navigable waters. Gladys Hari Leiva, a long-time resident and hotel owner, noted that while locals are accustomed to fluctuations, floods now arrive at odd times, and heat intensifies, signaling broader climate impacts.
The roots of the border conflict trace back to early 20th-century agreements, particularly the 1922 Salomón–Lozano Treaty and the 1934 Rio de Janeiro Protocol, which defined the Peru-Colombia boundary along the Amazon’s deepest navigable channel. However, the river’s natural dynamism created new land like Santa Rosa, which neither side anticipated. Peru claims the island, arguing it was part of ChinerÃa Island granted to them under the treaty, and in 2025 designated it a district to enhance public services and reinforce sovereignty.
Colombia disputes this, contending that Santa Rosa did not exist when treaties were signed and that river shifts place it in Colombian territory. Tensions escalated in 2025, with former Peruvian President Dina Boluarte visiting the island to assert Peru’s claim, while Colombian President Gustavo Petro criticized Peru for ‘appropriating’ the land on social media. These diplomatic moves highlight the island’s symbolic and strategic value at a key crossroads for Amazon trade and travel.
Despite its modest fame for tourism and gastronomy, drawing visitors to riverside eateries, Santa Rosa lacks basic infrastructure. Electricity only recently became available year-round, sewage systems are absent, and residents rely on wells for water, with healthcare remaining precarious. The island’s economic growth contrasts with its underdevelopment, yet many residents, like Leiva, cherish it as a multicultural haven where Peruvian, Colombian, and Brazilian identities blend seamlessly.
Environmental scientists warn that climate change could accelerate the island’s transformation, with droughts and floods potentially speeding erosion or land buildup. Paulo Olivas, an ecologist at Florida International University, emphasized that such uncertainty complicates long-term planning for both residents and governments. As the river continues to move sand and shoreline, Santa Rosa’s future remains as fluid as the waters that sustain it, posing ongoing challenges for border resolution and community resilience.