Upon arrival to the Sanctuary, you can see a coastal plain formed by flat floor valleys drained by streams that provide fresh water to the coastal lagoons. There are four swamps separated from the sea by sand bars: Manzanillo swamp, Laguna Grande, Chentico swamp and Navío Quebrado lagoon, into which the Tomarrazón-Camarones river flows. There are other intermittent bodies of water in the area that originate during rainy season such as Pozo Redondo, Barranquita and Marucha, and some minor currents such as Perico stream and Laguna Grande, which are of great importance to the estuaries. At the end of the rainy season, the intense waves of the sea carry large deposits towards the beach until the mouths of the lagoons are again closed.