Bathophobia

Bathophobia (from the βάθος, báthos, "depth" and φόβος, phóbos, "fear" is an irrational fear of depths, which may include oceans as well as trenches, long hallways, canyons and basements. As with most phobias, bathophobia causes an emotional reaction, a form of anxiety or a panic attack.

Causes of Bathophobia
Most phobias commonly involve anxiety, although the degree is individual-specific. Minimal symptoms include feeling nervous, uncomfortable, or nauseated. Severe cases may be indicated by panic attacks, death, or anxiety so severe that the individual appears paralyzed and/or dead.