The pillboxes associated with the Masefau Defensive Fortifications, a World War II-era monument, was listed on the U.S. National Register of Historic Places in 2012.
The inner part of Masefau Bay is fringed by a coral reef, which limits the anchorage area and leaves only a narrow channel for small boats to access the beach.
Formed at depths of 92–610 meters beneath a volcanic rift zone, the dike complex is intersected by thin, faulted basaltic lava flows dipping 10–20° NW.
[3] Mangrove forests are found at four locations on Tutuila Island in American Samoa: Masefau, ʻAoa, Nuʻuuli, and Leone.
Although its landform resembles that of coastal marshes, it remains connected to the sea through a stream channel, allowing the tidal inundation essential for the mangrove ecosystem's survival.