One of the most visible features along Waimânalo Bay is Waimânalo Beach, which, with an overall length of nearly 5.5 mi (8.8 km), is the longest stretch of sandy shoreline on O`ahu. Waimânalo Beach is a popular sun-bathing and swimming area, especially where its sandy bottom slopes gently offshore. Lithified dunes occur on the alluvial plain behind the beach. Located just north of Waimânalo Beach, Bellows Air Force Station, with its several ditches, streams, and wetland areas, provides habitat for endangered waterbird species. Shoreline access permits moderate to heavy fishing for ulua, pâpio, weke, and 'ô'io along the length of Waimânalo Bay.

McAllister (1933, p. 192) records the existence of a sea pond which was said to have been 500 feet long and 50 feet wide. "A line of stones, submerged at high tide, but visible at low tide indicates its former extent." The ali`i kept turtles in the pond. Charles Aiona said that this ali`i was so fond of turtle meat that everyone in the district was required to bring any turtles they caught to him. (1)

An exceptionally wide, submerged reef extends offshore of Waimânalo Bay. The reef margin, approximately 5,000 ft (1,500 m) from Waimânalo Beach, varies in depth between about 15 ft (5 m) and scattered shoals. Depths exceeding 30 ft (10 m) occur in a broad, lagoon-like depression behind the margin. This entire feature is suggestive of a submerged barrier reef. The bottom of the submerged reef flat includes areas of considerable relief and sand, with patchy coral cover. Only a few species of fishes are abundant here. The entire coast is subject to high surf and tsunami (tidal wave) flooding.