I love to snorkel in tropical waters and have done so several times in various locations in Hawaii, the Caribbean, Florida, etc. This beach is listed as a "beginners" beach and is great for anyone. It is a protected bay that is best to snorkel in at high tide because the various rocks/reefs are too close to the surface at low tide. It has abundant reef fish of various types and is frequented by turtles!!! In fact, the turtles like to sun on the beaches in Hawaii, and I saw two which was exciting. The scenery at the beach is just about as good as it gets in Hawaii with plenty of palm trees, soft sand, and lots of room for everyone. It has a covered kitchen area that can be booked for a group meal or just enjoy sitting in the shade at the tables there. There is a vendor to rent snorkeling equipment there at the beach if you haven't brought your own or rented them from somewhere else.
Snorkel Bob's is a great resource as they have perscription lens in some of their masks that can greatly enhance the "viewing" of the fish when your snorkeling. Plus, if you are traveling to any of the other islands, you can return your equipment at any location on any island. Pay the little extra to get a "dry" snorkel. It has a gang valve on it that prevents the water from coming down the tube and nearly drowning you if you're not careful when you turn your head to look at fish on one side or the other of you.
There are many great places to snorkel on the island, but because of the lava making getting to the water rather treacherous, it's worth finding and using the best beaches on the island. SO GO ENJOY, EVERY DAY WHILE YOU ARE THERE!!!!