Explore the Bay, Hanauma Bay Education Program

Ocean Conditions

Physical Oceanography

The water temperature in Hawaii remains quite stable over the course of the year. In the winter the average water temperature is in the low 70's whereas in the summer it can get into the low 80's Fahrenheit. The reef at Hanauma bay is known as a fringing reef. This type of reef is the newest form of reef, growing out from the beach and sloping off into deep waters. The reef is divided up into a number of different zones the first being the reef flat area. The reef flat is all the rock like structure going from the beach up to the reef crest (the area where the waves are breaking). Typically the depth of this area is less than 15 feet. Biological zones also exist in Hanauma Bay, on the reef flat area the predominant type of reef building organism found is Coralline algae, which looks like reddish/brown rock. The dominant reef building organism found in the next zone (the shallow reef slope) is Lobe coral, the depth of this zone ranges from 10-35 feet. The third zone is the deep reef slope which can range from a depth of 20-70 feet. The dominant reef building organism in this zone is Finger coral, which happens to be endemic to Hawaii.

Ocean conditions and weather varies and can change quickly at Hanauma Bay and in Hawaii in general. Tides are constantly changing; along with the strength of currents, you should always be aware of the ocean conditions before getting into the water. Snorkeling becomes difficult with increased wave activity, check the local news or surf report for tides and wave activity on south and east facing shores. When conditions are rough, lifeguards generally ask that all snorkelers and swimmers do not go past the reef crest.

Check with lifeguards about beach and surf conditions BEFORE getting into the water. The ocean is very different from a swimming pool. There is reef, waves, and currents to take into account. If you are an inexperienced snorkeler or ocean swimmer, it is a good idea to stay close to shore and to stay in the shallow sandy areas until you feel comfortable with your equipment. The best way to see fish and avoid getting cut by the reef is to swim along the edges of the reef and not directly over top of it.

Parents should take extra care to supervise their children in the water and along the shoreline. Make sure to bring lots of sunscreen as shade is limited. For extra tips, please visit the City and County website (http://www.hanaumabayhawaii.org) and/or the Ocean Safety website (http://www.aloha.com/~lifeguards/).

City and County lifeguards are on duty in white towers on the beach from 7 am until 5:30 pm.

Last updated June 3, 2004
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