A similar case with a telling difference is Anchorite Rock in NZ's Hauraki Gulf: https://en.wikipedia.org/wiki/HMS_Anchorite_(P422)#Service https://en.wikipedi

A similar case with a telling difference is Anchorite Rock in NZ's Hauraki Gulf: https://en.wikipedia.org/wiki/HMS_Anchorite_(P422)#Service https://en.wikipedia.org/wiki/HMS_Anchorite_(P422)#Service The difference being that this rock was already known by some local fishermen, who had allegedly refrained from informing the Hydrography Office because it was an excellent and little-known fishing ground. (jokingly) lacking patent protection for fishing spots, they opted for a trade secret.