Mokumanu is an offshore island near Mokapu Point on the northern end of Kailua Bay. A channel approximately 3/4 of a mile is deep and often turbulent comes between the island and the point. A total of 21 acres the island is actually two parts; the largest at 18 acres and the smaller part at 3 acres. The entire island measures 1350 feet long by 700 feet wide. The highest point is about 202 feet above sea level but the average is 165 feet.

 

  

 
 

Mokumanu is a protected State Seabird Sanctuary since 1945 with no landing permitted. The least accessible of any of Oahu offshore islands landings are possible on the rocks during very calm conditions (which are few) to the smaller part. The larger part has steep seacliffs surrounding more than half of the island. However, the lack of access make for an ideal place for nesting seabirds. One counting recorded over 43,000 nesting adult seabirds of 11 species!

  
 
 
Mokumanu is probably the most inaccessible of all the offshore islands of Oahu.