Sculpt Terrain

On Unity, we are going to be making 3D scenes for our games and we were experimenting with it. We were making a vacation scene for our 2nd time and it wasn't to hard as the first time, but still hard to remember the layouts. When I made my terrain I had trouble making the volcano with out the sides of it being deleted from a tool I was using. Also I tried to add movable water in the water, but it didn't want to work, only smoke came out.But everything seemed simple so far, I just have a feeling that everything will soon be complicated.