Ehh i tried it not so good btw fragmen im camo xD

The water one isn't scary. You should put wooden pressure plates under it, that are ontop of more sand, and under that sand is TNT!!!!!!!!! Break the sand and you go BOOM.

I don't think the water below the sand is scary, so I think you should replace it with 1 layer of sandstone. When you break that you should fall into a temple with pressure-plates that are redstone connected to dispensers with spawn eggs that spawn blazes and witches. That would be scary! Maybe even Fire Charges! Make sure the temple is made of cracked stone bricks, mossy stone bricks and stone bricks so it looks like a dungeon. Please also make sure that if you add this, make it as big as the biome and be able to get lost because of thousands of rooms. <:)

add a lava biome