Two Step is the public swimming snorkeling area right next to the place of refuge national park. Enter the park and leave your vehicle there, then walk back out and snorkel until you are borderline hypothermic, then go back and check out the park exhibits while you warm up. The park has restrooms, but there are no showers or anything anywhere so you are going to be salty. It is worth it. The park exhibits are great, and the snorkeling is superb, especially if you like to dive down a bit. Huge coral heads, numerous fish, and extremely good visibility, especially if you get a little bit away from the crowds.
If you are looking for a place to flop and get a tan, this is pretty rocky. The main attraction is a natural couple of steps in the rock that make getting in and out almost as easy as climbing onto a dive boat. A few keiki pools for younger kids make this a great spot for all ages of folks comfortable in the water.
I've been here twice in 6 years, and it has not degraded much, but the amount of sunscreen in the water column is not helping anything. If you can protect yourself with a shirt and other alternatives, the fish and coral will thank you.