Invisible Residents

Ivan T. Sanderson's Invisible Residents — the original investigation into Unidentified Submarine Objects: craft observed entering and exiting water that defy conventional explanation. Published 1973. Sanderson was a Fellow of the Zoological Society of London and brought genuine scientific credibility to his anomalous investigations.

A serious and scarce title. Sanderson's case for an intelligent non-human presence operating in Earth's oceans is methodically built and genuinely strange.