[zeteo]

I've found a bit more information about the topic in a publicly available research article [1]:

"A depth of only 25 fathoms is quite enough to give some surface indications: coloration, wave phenomena, perhaps fauna. Is this the explanation of the ghost island? Some lost traveller, perhaps en route from Yap to Guam, seeing and remembering these phenomena, later reifying them as an inhabited land? Or is it possible that a real island once existed here, as the Carolinians say? [...] Any Carolinian navigator worthy of the name can give a whole set of radiating courses under all the navigation stars from every island of the Carolines, not just from Kaafiror. [... N]avigators do learn them, together with the courses from real islands, and they make no distinction among them. It is perhaps not altogether in the realm of fantasy to speculate that the curriculum of the schools of navigation was established in a time when Kaafifor was more than a discolored patch of water."

[1] https://micronesica.org/sites/default/files/the_ghost_island...