Wiktionary
thalassophobia
n. A morbid fear of the sea.
Wikipedia
Thalassophobia
Thalassophobia Greek: thalassa, "sea" and φόβος, phobos, "fear") is an intense and persistent fear of the sea. Thalassophobia is a clinical phobia generally classified under specific phobias, fear of a single specific panic trigger. Symptoms for thalassophobia are the same as for most specific phobias.
Although it is a clinical phobia, it often accompanies other anxiety disorders. In some cases anxiolytic medications may be prescribed or Cognitive Behavioral Therapy (CBT) may be indicated.
Thalassophobia can include fear of being in large bodies of water, fear of the vast emptiness of the sea, and fear of distance from land.