What happens when an active volcano under the sea (below sea level) Erupts?

We all know what happens when a fully active volcano erupts. It spits molten lava into the sky and flows down to the base and surrounding environment.
We've seen this countless of times on documentary channels or even in movies like 'Pompeii' the movie.
Personally I'd like to know what happens when the volcano is under water and erupts under water. Does it make the water boil? Does it kill the fishes? Does the lava solidify immediately because of the water?. A lot of questions I'd like answers to and I'm sure others would want to learn as well