What do you call a fear of deep bodies of water such as the ocean or sea?

Thalassophobia is a type of phobia characterized by a persistent and intense fear of deep water, such as an ocean or a lake.

People with thalassophobia either avoid deep bodies of water altogether or endure them with overwhelming anxiety. The level of fear they experience is extremely disproportionate to any actual danger.

While thalassophobia isn’t recognized as a distinct disorder in the Diagnostic Manual of Mental Disorders, fifth edition (DSM-5), its symptoms fall under the diagnostic criteria for “Specific Phobia: Natural Environment Type.”