You saw The Abyss when you were little? Either that, or you were raped by a submersibles pilot, & repressed the memory. Definitely one of those two though
The first one looks like the high gravity training dome Dr. Briefs made for Vegeta. If you're scared, it's probably because Vegeta is a badman.
Why not describe what it is about the pictures that scares you? Then we can tell you what your fear is. Maybe you have a fear of drowning?