East of Honolulu and southeast of Kuapa Pond on Oahu, the snorkeling at the Hanauma Bay Beach Park in the Hanauma Bay Nature Preserve Park is known for its horseshoe bay filled with reefs to explore. The bay is a old volcanic crater and contains flat algae-covered reefs. The Hanauma Bay snorkeling is protected from the large ocean waves for a gentle snorkel experience. When snorkeling off Hanauma Beach, you can expect to see millet-seed fish, raccoon fish, thread fin, butterfly fish, reef trigger fish, wrasse, convict tang, unicorn fish, squid, white-tipped reef sharks and occasional sea turtles.
For beginners, the inner bay adjacent to the beach is protected by the inner reef structure resulting in a calm, waist deep snorkeling experience. This protected inner bay extends about 150 feet offshore. With it’s sandy bottom and lack of current, the inner bays tends to have poor visibility and is usually quite crowded. Since the water of the inner bay is only a couple feet deep, it is not recommended to wear fins since they can make it difficult to stand in the shallow water if you get into trouble - each year, there are several drownings in this inner bay since people can not stand with the fins on.
For advanced snorkelers on calm days, you could proceed out the central channel to the outer bay. This central channel was actually cut into the reef many years ago for routing an undersea cable. The outer bay is still protected by a submerged reef system, but when the waves are up and the wind is blowing, the outer bay can be quite treacherous. Hence, the first outer bay is known as the Witches Brew. But, if you are lucky and come on a calm, sunny day, you will be treated to exceptional visibility -- matter of fact, the best visibility for a beach-accessed dive on Oahu. One could easily spend a couple hours snorkeling Hanauma bay while exploring both the inner bays and the outer bay. Keep in mind that in the past you were allowed to hike along the ridges and shores to access the north and south shoreline dive sites; this is now prohibited.
TIP: the Hanauma Beach snorkeling is occasionally closed due to currents carrying jellyfish. Make sure to check with the park office before coming out to make sure it is open.
To reach the best snorkeling on Oahu by air, you will need to fly into Honolulu International Airport (HNL) which is located just on the west side of Honolulu. There are direct flights into Honolulu from the US, Australia, New Zealand, American Samoa, Tahiti, Japan and Fiji. In addition, there are inter-island flights to all the main Hawaiian Islands.
The Hanauma Bay Beach Park is located at 7455 Kalanianaole Highway about 10 miles east of Waikiki via H-1 east (which becomes Highway 72). It is open dawn to dusk, but closed on Tuesdays. The parking area is on the ridge above the beach and requires a nice hike down, or you can pay for the shuttle down.
The best way to get to Hanauma Bay from Waikiki is to take The Bus #22 eastbound. It starts around 8:30am and runs roughly hourly except for mid-morning and mid-afternoon where there are a couple 30 minute laps. The bus is known to be very crowded, so you’ll want to get on at the first stop at the intersection of Kalakaua Avenue at Saratoga. It’s only a couple bucks each way but exact change is required. The bus usually takes about 30 minutes to reach the bay. For more information, call them at (808) 848-5555.
There is a nominal entrance fee and visitors must watch a short 19 minute video in the Marine Education Center before entering. Hanauma Bay Beach Park is by far the most popular and crowded snorkeling dive site on Oahu with several thousand snorkelers per day and over a million snorkelers annually. So, make sure to arrive very early for parking and for some solitude (think before 7am!). There are limited guest services down by the beach, so get what you need from the visitor center on the ridge above.
There is good snorkeling on Oahu year-round. But, the conditions very around the island depending upon time of year due to winds and currents. The north shore snorkeling dives are best from June through September and are usually closed out the rest of the year due to high surf. The south shore dive sites are best from November through May. The main exception is Hanauma Bay, which tends to be good year-round since it is very protected.