| Supply Reef | |
|---|---|
| Summit depth | −8 m (−26 ft) |
| Pronunciation | Northern Mariana Islands, United States |
| Location | |
| Coordinates | 20°08′N 145°6′E / 20.133°N 145.100°E |
| Geology | |
| Type | Submarine volcano |
| Last eruption | September to December 1989 |
Supply Reef is a submerged circular reef of volcanic origin in the Northern Mariana Islands chain, about 10 kilometres (6 mi) NW of the Maug Islands. Presently this igneous seamount is roughly 8 metres (26 ft) below the ocean's surface and about 100 m (300 ft) in diameter.