USOs Not UFOs Have Been the Greatest Threat to the Navy
"As long as there have been sailors there have been tales of sea monsters lurking in the depths that could snatch crewmen and crush ships. There are an unknown amount of animals in the ocean that have yet to be identified. Recent discoveries such as the humpback angler fish and the ninja lanternshark demonstrate that there are still plenty of things in the oceans that can fuel nightmares. It is also true that USOs (unidentified submerged objects) not UFOs have presented the Navy with the greatest hazard."
https://www.usni.org/magazines/naval-history-magazine/2022/august/usos-not-ufos-have-been-greatest-threat-navy