[defrost]

... and the cold war era submarine communications base:

Naval Communication Station Harold E. Holt https://en.wikipedia.org/wiki/Naval_Communication_Station_Ha...

    It is generally agreed that Holt's disappearance was a simple case of an accidental drowning, but a number of conspiracy theories surfaced, most famously the suggestion that he was a spy from the People's Republic of China and had been collected by a Chinese submarine.

-- https://en.wikipedia.org/wiki/Disappearance_of_Harold_Holt