The Great Flood.

Covering an area larger than many countries, the Pantanal is a gently sloping basin that transforms from a terrestrial savannah into a vast inland sea every year.

The Pantanal’s existence is governed by the **Flood Pulse**. During the rainy season, water from the surrounding highlands flows into this massive depression. Because the basin has a remarkably low gradient, the water drains extremely slowly, creating a sprawling labyrinth of marshes, lagoons, and flooded forests.

Biological Concentration

As the floodwaters recede during the dry season, the Pantanal undergoes a dramatic transformation. Water is confined to shrinking pools, which concentrates fish and aquatic life into high-density zones. This "buffet" triggers a massive influx of predators, making the Pantanal the densest concentration of jaguars and caimans on the planet.

The Silt and the Carbon

Wetlands like the Pantanal are critical **carbon sinks**. The waterlogged conditions slow down the decomposition of organic matter, allowing thick layers of sediment and peat to build up over thousands of years. This process locks carbon away from the atmosphere, while the vegetation acts as a giant natural filter, purifying the water as it moves through the basin.