Also known as Di'nem Island in the native language,[2] Diogo is a lone rock rising out of the sea, with steep cliffs on every side, and dangerous currents make landing there practically impossible.

It is an extinct volcano which has suffered heavily from marine erosion.

[3] Diogo is a small, round island over 1,795 feet (547 m) high, about 3⁄4 mile (1.2 km) in diameter, lying 3.5 miles (5.6 km) southeastward of Itbayat Island.

[3] It is listed as an inactive volcano[5] by the Philippine Institute of Volcanology and Seismology.

In old Spanish maps, the name of the island was listed as Isla Diego or Rodonta.