[1] The islands are subject to tidal surges caused by cyclones and volcanic activity from nearby Tinakula volcano.
[2] The islands or atolls of the group are: Numa Miombilou or "Great Reef" is one continuous shoal, extending about 25 km (16 mi) west of Nifiloli.
About 10 km (6.2 mi) to the south of this shoal are 4 small coral reefs: Separated from these groups are what are called the "outer islands": The total population of the Reef Islands is about 5,600, according to 2003 estimates.
This includes a Polynesian community, believed to be descendants of people from northern Tuvalu.
The remaining Melanesian (non-Polynesian) population speaks Äiwoo, a member of the Reefs–Santa Cruz group of Oceanic.