Moku Manu, or "Bird Island" in the Hawaiian language, is an offshore islet of Oahu, three-quarters of a mile off Mokapu Peninsula. Moku Manu and an adjacent small islet are connected by an underwater dike. The island was formed from debris flung from a vent of the nearby Kailua Volcano. Its highest point is 202 feet (62 m) high, bordered by near-vertical cliffs on many sides. Moku Manu is protected as a state seabird sanctuary like its neighbors to the south, Manana, Kāohikaipu, and Mōkōlea Rock. Regardless, landing by boat is nearly impossible due to the lack of a safe beach. (Wikipedia)

Moku Manu's isolated nature makes it an amazing dive site with impressive rock formations and a large variety of sea life.  This is an easy dive, but it's isolation, depth, and darkness inside the sea-caves make it appropriate only for advanced certified divers.  

Accessable: Boat only 

Depth: ~75f/23m max

Considerations: Must have permission and may not land on island (not that you could anyway).  

Conditions must be ideal or swells can create hazardous conditions

Dive Light is mandatory inside the sea cave.