Moonstone Beach is hard to find if you don't know what you're looking for, but it's AMAZING. Awesome HUGE rocks/cliffs rising out of the water. Caves, inlets... a wonderful beach. Luffenholtz is right next door and that is equally amazing, but you'll need to take quite a walk down to the beach itself.
Moonstone Beach is a great place to spend a sunny afternoon. It is a very beautiful beach thus is a popular hang out on nice days in Humboldt. There is a cave, a channel going through the beach and a lot of rock formations. I always have an adventure when I go here.