For my unity test, I did a scene with a nice looking skybox, a boat in the water, and a whale underneath. I was at first attempting to make it so there was a net on the whale, as if someone on the boat was hunting it, but I couldn't figure out how. With the boat, I added a engine noise that has a range of about 50 meters. I have many trees and water surrounding the area, giving it a nice, serene look. I didn't add those myself, but I found a scene that had the trees, added the water, and deleted the trees that were inside of the water to make it more realistic