Thalassophobia
Thalassophobia is an intense and persistent fear of the sea. Thalassophobia can include fear of being in deep bodies of water, fear of the vast emptiness of the sea, of sea waves, sea creatures, and fear of distance from land.
Thalassophobia is different from aquaphobia because while aquaphobia is the fear of water itself and may present with weather events or relatively small amounts of water, thalassophobia is a fear of bodies of water that appear vast, dark, deep, and dangerous.
