Northeast of Honolulu and southeast of Kailua, the snorkeling at Halona Beach Cove is located inside this protected beach. It is a small snorkeling area that is best when the winds are not coming from the east. There are not big reef formations, but the rocks on the side are very interesting.
To reach the Halona Beach Cove snorkeling from Waikiki, head east on H-1 to Highway 72. Continue past Hanauma Bay and look for the Halona Blowholes parking area. After parking, you can walk down to the beach.
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, Halona Beach Cove is the 23rd most popular snorkel dive spot of all 23 snorkeling dives in Oahu.