Tafuna-Leone Plain

The Tafuna-Leone Plain forms the largest contiguous expanse of level, developable land in American Sāmoa. It is the only significant flat land on Tutuila Island. Much of Tutuila Island, especially its mountainous northern region, consists of older volcanic formations characterized by low permeability. In contrast, the Tafuna-Leone Plain in the southwest is composed of more recent volcanic rocks with higher permeability.

Most of the lowland rainforest on the Tafuna-Leone Plain has been cleared, with only a few remaining fragments scattered across the area. Adjacent to the Fatuoaiga Catholic Church Center and the Tia Seu Lupe Historic Monument at Ottoville, a 20-acre reserve protects the island's last remaining lowland rainforest on Tutuila.

It is the largest expanse of level terrain on Tutuila Island, covering approximately 35 square kilometers (13.5 sq. mi.). Formed by extrusive volcanic activity that overlaid an older eroded surface, it contains the island's only extensive aquifer.