The Kerala backwaters are a network of interconnected brackish lagoons and lakes lying parallel to the Arabian coast. The backwaters were formed by the action of waves and shore currents creating low barrier islands across the mouths of many rivers flowing down from the Western ghats. The backwaters have a unique ecosystem: freshwater from the rivers meet the seawater from the Arabian sea. The freshwater is used for agricultural purpose. Varieties of aquatic animals like crab, frogs, mudskippers, turtles and also birds such as kingfisher, darters and cormorants live alongside the backwaters. The kettuvallams also is known as boathouses in the backwaters are one of the major tourist attractions. Previously the kettuvallams were used as grain barges to transport the rice harvested in the fields alongside the backwaters. There are also many ferry services to connect most of the banks on the backwaters. The backwaters support the local economy the connecting regions.