I read a fantastic poem a month ago called Grass Widow by Isabel Galbraith and found a word I'd not seen before. Calenture. The poem answered my questions about the word, "Sailor's delusion/The sea a green plain" and so I didn't go any further with it. Then I came across a not-so-great album by the Australian rock band, The Triffids, which was titled, Calenture. So, through Google Books, I went to the Lexicon Medicum: Or, Medical Dictionary from 1829 and found this wonderful line: "A febrile delirium, said to be peculiar to sailors, wherein they imagine the sea to be green fields and will throw themselves into it if not restrained."
I looked around some more and found reference to calenture in Moby Dick, thanks to the William Gilbert Homepage. It reads:
"These are the times, when in his whale-boat the rover softly feels a certain filial, confident, land-like feeling towards the sea; that he regards it as so much flowery earth; and the distant ship revealing only the tops of her masts, seems struggling forward, not through high rolling waves, but through the tall grass of a rolling prairie: as when the western emigrants’ horses only show their erected ears, while their hidden bodies widely wade through the amazing verdure."
So I wanted to say thank you to Isabel Galbraith for making me spend nearly an entire day of work reading about crazy sailors.