Unidentified Submerged Objects (USOs)
Objects that move through water at speeds and depths inconsistent with known vehicles, often emerging from or diving into the ocean without slowing at the air–water boundary. The Navy admits some are 'unidentified.'
A USO is an Unidentified Submerged Object: roughly, a UAP-class anomaly observed moving in water rather than air. The Navy classification used by AARO and others sometimes treats USOs as a sub-category of UAP; the deeper lore reaches back to the 1960s and treats them as their own phenomenon.
The case literature has a consistent shape:
- Catalina Channel, CA — long-running rumor of “supercarrier-sized” submerged structures and a sustained Navy interest in the area; some retired pilots and ex-Navy personnel speak about a submerged base ~3,000 ft off Malibu. None of this is officially acknowledged; the area is a sustained Navy training cordon.
- Puerto Rico Trench — multiple reports of objects entering water at high speed and not resurfacing, dating from Coast Guard and naval observations.
- Mariana Trench / Western Pacific — sonar anomalies at depths submarines cannot reach.
- Lake Baikal, Russia — Soviet-era diver reports of large humanoids in the deep lake, declassified in the 1990s.
- Hessdalen, Norway — primarily atmospheric, but the same broad “place where the rules sag” character.
The most-quoted modern advocate is retired Rear Admiral Tim Gallaudet, former head of the National Oceanic and Atmospheric Administration, who has openly argued USOs are a serious gap in maritime intelligence and a top science priority.
The transmedium claim — that an object can move from air to water (or vice versa) without slowing or generating the expected acoustic signature at the boundary — is the specific behavior that makes USOs the strongest single piece of evidence against any known propulsion model. The Tic-Tac sensor track included transmedium behavior; that’s what made the Princeton’s radar operators take it seriously.
Worldbuilding payoff: USOs solve a lot. They give you a geography that’s plausibly always-on (the ocean is enormous, transparent only at the surface, and impossible to police), an organizational explanation for why the Navy keeps things quieter than the Air Force, and a clean line into the cryptoterrestrial hypothesis: the bases aren’t on the moon — they’re 6,000 ft down off Catalina.
Notable & intriguing
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Unidentified Submerged Objects (USOs) became a U.S. Navy operational category most prominently after the 24 December 2019 UAP encounters off the California coast — the “USS Omaha incident” — which produced FLIR footage of a spherical object descending into the water and continued tracking by sonar.
DoD-released FLIR footage, 2021; Corbell, On the Trail of UAP, 2022.
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The Soviet Navy’s Recommendation on the Encounters with Unidentified Submarine Objects (1990s, signed by Vice-Admiral Yuri Beketov) included over 50 documented Cold War encounters with submerged objects exhibiting non-conventional behaviour; portions were released to UFO researcher Vladimir Azhazha and excerpted in Pravda in 2002.
Pravda (Russian edition), 14 Feb 2002.
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The U.S. Navy formally amended OPNAVINST 3100.6J in March 2019 to establish a UAP reporting protocol — the first formal Navy reporting protocol for the phenomenon since the 1950s.
U.S. Navy OPNAVINST 3100.6J revised, March 2019.
Public-record items already documented about this subject. Folklore is labelled. Sources cited where the specificity warrants it.
Sources
Methodology assessments software-engineering rigor turned on the claim
The transmedium claim as a Petri net (the load-bearing physics question):
Places: P1 ObjectInAir (•)
P2 ApproachingSurface
P3 InWater
P4 ExitingWater
P5 SteadyInWater
Transitions (the controversial ones marked ‼):
T1 Descend P1 → P2
T2 PenetrateSurface ‼ P2 → P3 — no sonic boom, no acoustic signature
T3 SubmergedTransit P3 → P5
T4 SubmergedRise P5 → P4
T5 ExitSurface ‼ P4 → P1 — same boundary problem in reverse
T2 / T5 are the load-bearing transitions. Any known propulsion would generate either (a) a hypersonic shock at the air/water boundary, or (b) cavitation collapse with massive sonar signatures. Reports of these transitions WITHOUT those signatures are the strongest single physical-implausibility argument in the entire phenomenon corpus.
Falsification path: a single confirmed instance of transmedium with the expected shock/sonar signature → conventional vehicle. A single confirmed instance WITHOUT → something is off. The Princeton’s radar/sonar data on the Nimitz incident is the closest we have to the second.