Kaʻula Island, also called Kaʻula Rock, is a small, crescent-shaped offshore islet in the Hawaiian Islands.
It is located 23 mi (37 km) west-southwest of Kawaihoa Point on Niʻihau, and about 150 nmi (278 km) west of Honolulu. The island is the top of a volcanic tuff cone that rests on top of a larger, submerged shield volcano. At its highest point, the island reaches a height of 548 ft (167 m).  The ocean has carved large sea cliffs on the sides of the island. There is a large cave on the northwest side of the island called Kahalauaola (Shark Cave). 
The United States Census Bureau defines Kaʻula as Census Tract 411 of Kauaʻi County, Hawaiʻi. The 2000 census showed that the uninhabited island had a land area of 158.2 acres (0.640 km2; 0.2472 sq mi).  Because of erosion, the island is slowly shrinking.
Kaʻula, which he spelled as "Tahoora", was one of the first five islands sighted by Captain James Cook in 1778.
The island has been used as a bombing range by the United States Navy since at least 1952. Inert ordnance is currently used, although live explosive ordnance has been used in the past. There is a risk of unexploded ordnance on the island. Permission from the U.S. Navy is required to land on the island. In 1978, over the objection of the U.S. Navy, the state of Hawaiʻi claimed ownership of Kaʻula and named the island a State Seabird Sanctuary. A final determination of ownership has not yet been made, and the Navy still uses the southeast point of the island as an aerial bombing and strafing target. 
- Tabrah, Ruth M. (1987). Niʻihau, the last Hawaiian island. Press Pacifica. ISBN 0-916630-59-5.
- Tava, Rerioterai; Keale, Moses K. (1998). Niihau, the traditions of a Hawaiian island. Mutual Publishing. ISBN 0-935180-80-X. Archived from the original on 2013-05-24. Retrieved 2009-05-28.
- Offshore Islet Restoration Committee, Kaula
- Kaʻula Island
- Nautical Chart Containing Kaʻula Island
- Kaula Rock Photos Photographs of Kaʻula Island, May 2008