Eretoka spans 2.3 kilometers in northeast-southwestern direction and has a maximum width of 670 meters.

The center of the island forms a cap of coral lime over stratified pumice and is 90 meters high.

Around the island center extends a wide and flat area of sand and limestone, which was lifted over the water surface during the last elevation of the seabed.

Roy Mata, a powerful 16th-17th century Melanesian chief, was buried in the island.

The grave was studied by French archaeologist Jose Garranger in 1967, who analyzed the local folklore.