Years ago, the verb spoon had a now obsolete meaning, “to run before the wind, to scud.”
The origin of this sense is not known, but the similarity in sound to spume (from the Latin spuma, “foam”) led to an alternate spelling, spoom.
Then, through some confused process of reasoning quite difficult to reconstruct, the two meanings, “foam” and “scud,” were connected in spoondrift, the sea foam generated by high winds.
As though this weren’t sufficiently complicated, there now came the problem of dialectal pronunciation.
In parts of England, spoon was pronounced speen; in other parts, spin.
From the latter, spoondrift became spindrift, and this, some seventy-five years ago, became stabilized as the accepted spelling and pronunciation.