Ko`olaupoko Shores and Reefs

Nearly half of the shoreline of the Ko`olaupoko District occurs inside of Kane`ohe Bay. The largest embayment in the Hawaiian Islands, this feature presumably resulted from erosion of the Ko`olau shield volcano, particularly during a low stand of the sea. Secondary volcanic eruptions have played a prominent role in the local geology of two regions: Makapu`u and Mokapu Peninsula. Between these points, are the broad bays of Kailua and Waimanalo, where calcareous beach sand is the predominant shoreline type, interupted by a few basalt headlands.

Numerous small islands occur off the coast. Isolated remnants of Ko`olau basalts (sea stacks) are represented by Na Mokulua, Moku o Lo`e, and Mokoli`i. Manana and Moku Mana are tuff cones resulting from secondary volcanic eruptions. Cones of mostly basalts, also representing secondary eruptions, occur as Kaohikaipu and Mokolea Rock. Limestone islets are either raised reef rock such as Popoia, consolidated dune sand such as Kekepa and Kepapa, or unconsolidated sand such as Ahu o Laka.

Fringing reefs occur off much of the coast, but the reefs off Waimanalo, Lanikai, and Kualoa have submerged margins (depths exceed 2 meters). The fringing reef in Kane`ohe Bay, on the other hand, has a classic form: a shallow, consolidated limestone margin behind which is an extensive flat of reef rock and rubble grading to sand flats near shore. Kane`ohe Bay is further distinguished in possessing the greatest concentration of patch reefs in the main Hawaiian Islands, and the only good example of a barrier reef in Hawai`i. The latter extends for most of the 5.5 miles (8.8 km) across the mouth of the Bay. Reefs are absent off Makapu`u and Ulupau, and are poorly developed and submerged, or generally absent in much of Kailua Bay and off North Beach (Mokapu).

Ahupua`a of the Marine Ring
  • Kualoa
  • Hakipu`u
  • Waikãne
  • Waiãhole
  • Ka`alaea
  • Waihe`e
  • Kahalu`u
  • He`eia
  • Kãne`ohe
  • Kailua
  • Waimãnalo
  • District Map


    SOURCE: modified from AECOS, Inc.1979. O`ahu Coral Reef Inventory. Part B. Sectional Map Descriptions, prep. for U.S. Army Corps of Engineers. p. 9