Northwest of Honolulu on Oahu, the Kaena Point State Park is popular for snorkeling. The isolated, mile-long Kaena Point State Park beach is on the western tip of Oahu. While it is not really known for abundant marine life, the water visibility is excellent especially further out where the water runs about 12 feet deep over the sand and flat coral. Marine life does include sea turtles, trigger fish, parrot fish, surgeon, moorish idol and butterfly fish.
The Ka’ena Point State Park is located just before the north end of the Farrington Highway where there is a small parking lot and roadside parking. It is about a 1 hour drive from Honolulu airport.
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.
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.
Overall, Kaena Point State Park is the 7th most popular snorkel dive spot of all 23 snorkeling dives in Oahu.