EDITORIAL GUIDE
~6 min read
Transmedium UAP — Objects That Operate in Both Air and Water
Transmedium behavior — the ability of an object to transition seamlessly between air and water without deceleration or surface disruption — is one of the five officially designated UAP 'observables' formalized by Luis Elizondo during his tenure at AATIP. It appears in multiple officially documented incidents in the U.S. military record, with the most evidential examples involving FLIR-equipped Navy aircraft and shipborne radar systems. Transmedium capability, if real, represents physics beyond current aeronautical or nautical engineering — and is specifically cited in congressional testimony as one of the features that distinguishes the highest-evidential UAP cases from conventional misidentification.
The Five Observables — Where Transmedium Fits
Luis Elizondo, during his directorship of AATIP from 2010 to 2017, formalized a framework for evaluating UAP encounters that has been cited in congressional testimony and adopted by AARO as an analytical baseline. The Five Observables are: (1) instantaneous acceleration — movement without apparent inertial effects; (2) hypersonic velocities without signatures — movement at speeds above Mach 5 without sonic boom, heat signature, or contrail; (3) low observability — objects that evade radar, IR, or visual detection selectively; (4) trans-medium travel — operation in multiple environments (air, water, space) without transition effects; (5) positive lift — maintaining altitude or gaining altitude without aerodynamic surfaces or visible propulsion.
Transmedium is the most dramatic of the Five Observables because it requires an object to function as both an aircraft and a submarine simultaneously — which are fundamentally incompatible engineering requirements in current human technology. Aircraft must minimize drag and maximize lift; submarines must withstand enormous external pressure and minimize cavitation. An object that moves seamlessly between air and water at speed is — by any current engineering standard — physically implausible.
The USS Princeton Radar Record — Two Weeks of Transmedium Tracking
The USS Princeton (CG-59), a Ticonderoga-class guided missile cruiser, tracked an anomalous object on its SPY-1 Aegis radar for approximately two weeks before the November 14, 2004 Nimitz intercept. The object was observed descending from approximately 80,000 feet to near sea level and re-ascending — repeatedly — in patterns that Princeton's Combat Information Center operators described as impossible for any known aircraft, balloon, or natural phenomenon.
On November 14, the object descended from 80,000 feet to the surface in seconds — a rate of descent that implied thousands of G-forces if a conventional aircraft performed it — then hovered just above the ocean surface with no visible rotor wash, no propulsion exhaust, and no surface disturbance. When Commander David Fravor and Lieutenant Commander Jimenez flew their intercept, they observed the object hovering over a churning circular disturbance on the ocean surface — described by Fravor as 'something under the water' generating the surface agitation. The object then left its position and disappeared. The combination of the radar track record and Fravor's first-person account — both in the public record — constitutes the most documented transmedium UAP observation in the official archive.
Pacific Submarine Incidents in the PURSUE Archive
The PURSUE program's May 2026 releases include multiple files referencing USS Transmedium Pacific 2023 — an incident in which a sensor-documented object entered the Pacific Ocean without surface impact trauma and maintained detectable depth at speeds inconsistent with any known submersible. The case classification is currently TOP SECRET with a PURSUE partial release noting the incident exists and its location coordinates, but the full sensor record remains classified.
This incident is in addition to the longer-documented Nimitz track. The USS Russell 2021 incident — in which Navy FLIR documented pyramid-shaped objects in close proximity to the carrier's flight deck before one apparently entered the ocean — is in AARO's unresolved case database with the FLIR footage partially released. The pattern across the Princeton (2004), Russell (2021), and Pacific Transmedium (2023) cases is consistent: Navy assets tracking objects that transition between air and water environments without conventional deceleration.
Scientific and Engineering Implications
The engineering implications of transmedium capability are the reason the Five Observables framework emphasizes it specifically. Current aerospace engineering faces a hard physics constraint at the air-water interface: the density difference between air (1.2 kg/m³) and water (1,000 kg/m³) means an object transitioning between the two at speed experiences forces equivalent to a wall of solid material. Aircraft entering water at cruise speed disintegrate. The fastest known conventional submarine (Alfa-class, Cold War era Soviet) reached approximately 40 knots underwater — less than 50 mph. The objects in the official record are described as entering and exiting water at speeds implying hundreds or thousands of knots.
Physicists evaluating transmedium claims have noted two theoretical possibilities: either the objects are generating a local field that neutralizes drag and pressure at the interface (a concept with no demonstrated mechanism), or they are experiencing a reference frame effect that is not yet understood in conventional physics. Neither explanation is testable with current instruments. The significance for UAP research is that transmedium behavior, if verified by the sensor records in classified portions of NARA RG 615 and PURSUE, would represent the strongest physical evidence that the objects exceed any known engineering capability.