Snorkeling Queens Beach and Sans Souci Beach are your best options on Waikiki Beach. Everyone wants to know where to snorkel in Waikiki. The closest snorkeling option is in the area south of the hotels in Waikiki that is designated a Marine Life Conservation District, just in front of Queens Beach. It begins at the Kapahulu Groin, the jetty that extends into the water at the intersection of Kalakaua Ave and Kapahulu Ave. It ends at the north wall of the Natatorium.
Just south of Queens Beach, the Waikiki Aquarium and the Natatorium is Sans Souci Beach, another close snorkeling beach. Across the road are both the Honolulu Zoo and the big, beautiful Kapiolani Park.
Snorkeling Queens Beach & Sans Souci Beach is okay. There is a little bit of coral and some fish to check out. Snorkeling is not safe here when there is a south swell, you need to always be cautious of currents and only go when the waves are calm. If you do try to go when there are waves, you are likely to have miserable visibility. The protection of the area in front of Queens Beach includes no fishing, so you are likely to see decent fish populations. You can read more about snorkeling Queens Beach on the Waikiki MLCD page.
There is flat reef in front of Queens Beach almost it's entire length. On the south end, past the wall that goes out into the water, but before Waikiki Aquarium's sea wall that parallels the beach, there is a sandy area that extends into the water a good distance. This is probably the easiest place to enter.
Sans Souci on the other hand is a nice wide sandy entry zone, with soft sand and a very gradual increase in depth.
From the entry for snorkeling Queens Beach, the best area is to the left from the beach (south) in front of the Waikiki Aquarium sea wall. Look from the beach with your polarized sunglasses for the channel you will head for. This dredged channel with a sandy bottom parallel to the beach about a hundred feet offshore is your destination. It is about 8 feet deep here and you will see the fish along the walls of the reef in this channel and along the wall of the Natatorium at the south end. You are not likely to see much live coral reef here, but there is some relief in the rock wall where the fish hide. The visibility varies depending on conditions. If the waves are up at all, the visibility will suffer and the snorkeling will be much less safe.
Once you have explored the Queens Beach channel, check to see if the tide is high enough to swim over the flat reef away from the beach further. On the chance that it is and if it is completely calm and you are a confident swimmer, you can head out to check out the outer reef edge; it's another 400-600 feet out and drops off quickly to 15-20 feet deep. The topography gets more interesting on this outer reef edge and there are more fish.
When snorkeling Sans Souci Beach, straight out there is more shallow flat reef that you can swim over if there are no waves and the tide is high. At most here it is 3 feet deep. The visibility is often pretty low, but you will be able to see some fish and a little bit of coral. Mostly the reef is covered in algae.
More interesting snorkeling from Sans Souci Beach is found by following the rock wall out on the left end of the beach. There are often more fish here and the visibility is better. It ranges from 4 to about 15 feet deep along the wall. Be careful because this area often has a fairly strong current, moving from the right side of the beach and exits this channel on the left. After swimming out along this wall, we found it twice as hard to get back in because of this current.
1. Head southeast on Kalakaua Avenue (one-way only in that direction) and pass all of the resorts.
2. Don’t veer left onto Monsarrat Avenue; instead continue straight on Kalakaua Avenue.
3. You will enter Kapiolani Park and see shortly on the right the Waikiki Aquarium and the Natatorium (see picture above). There is parking on the both sides of the split two-way road. For Queens Beach try to park north of the aquarium. For Sans Souci Beach, park on the south side of the aquarium near the Natatorium.
The area has restrooms, water, picnic tables, showers, shade and a lifeguard.