Trans-Medium Behavior: Known Physics vs Claims

Trans-medium UAP, the idea that a single craft slips from air to water or space to atmosphere without losing speed, sounds revolutionary, but the open record tells a more sobering story. AARO, ODNI, and NASA now track such claims, yet none has published a verified, multi-sensor case of seamless air↔water transitions. Instead, recent reconstructions

Executive framing

“Trans-medium” behavior refers to a single object or craft that operates across more than one physical medium for example, moving air – water (or water – air) or space – atmosphere without obvious loss of performance or signs of violent transition (splash, shock, cavitation collapse, etc.). U.S. government usage of the term now appears in official documentation, but the existence of trans-medium vehicles is a separate question from the mere presence of a term in policy text. The only responsible way to approach this topic is with a data-first lens: inventory what sensors actually show, compare those observables to aero/hydrodynamic constraints, and then categorize claims with transparent taxonomy and speculation labels.

This piece delivers:

• What modern sensors (EO/IR, radar, acoustic/sonar, space-based) have actually recorded.
• The physics of crossing the air–water interface: dynamic pressure, slamming loads, cavitation/supercavitation, and heating.
• Case-linked assessments grounded in official declassified reports and peer-reviewed hydrodynamics.
• A claims taxonomy with Verified/Probable/Disputed/Legend/Misidentification labels, plus Hypothesis / Witness Interpretation / Researcher Opinion where appropriate.
• Implications for collection, policy, and science.

What the official record says

1) Definitions and the official reporting picture

• ODNI 2022 Annual Report formally defines “Transmedium Objects or Devices” as those observed to transition between space and atmosphere, or atmosphere and bodies of water, and are not immediately identifiable. The definition’s presence signals reporting scope, not confirmation of existence. ODNI
• ODNI 2021 Preliminary Assessment highlighted that most reports likely represent physical objects and that 80 of 144 cases involved multi-sensor observations (radar, IR, electro-optical, weapon seekers, and visual). It also cautioned that a small subset showed unusual characteristics that might be due to sensor error, spoofing, or misperception pending better data. ODNI
• AARO’s public case-resolution program (2023–2025) now publishes data-driven analyses for specific incidents. Several widely publicized videos once touted for extraordinary behavior (including purported trans-medium signatures) have received non-anomalous or mundane resolutions after multi-disciplinary reconstruction and modeling. AARO
• NASA’s 2023 Independent Study concluded that data quality, calibration, and metadata are the limiting factors; NASA advocates multi-sensor, open-data approaches (including crowdsourcing) to achieve scientifically useful UAP datasets and explicitly notes that apparent anomalies often trace to sensor/platform motion and calibration limits. NASA Science

Takeaway: The term “trans-medium” exists in law and policy so the U.S. government can track such claims. Confirmation of trans-medium craft, however, requires high-fidelity, multi-modal evidence that withstands rigorous physical analysis, evidence not yet published in the open record.

What sensors actually show 

Electro-Optical/Infrared (EO/IR)

Strengths: Angular tracking, thermal contrast, persistent video.
Limitations: Parallax, glare/bloom, thermal crossover (times near sunrise/sunset when thermal contrast collapses), compression artifacts, unknown range/heading when metadata are incomplete.

• GoFast (2015) AARO’s 2025 reconstruction (working from the Navy FLIR display parameters and historical wind fields) estimated the object’s altitude ≈ 13,000 ft and intrinsic speed 5–92 mph, with the apparent high speed explained by motion parallax from a moving aircraft. No anomalous performance was found. AARO
• Puerto Rico/Aguadilla (2013) Frequently cited as “splitting” and entering/exiting water. AARO’s 2025 analysis reconstructed aircraft/sensor geometry and found two separate small objects drifting with the wind over land; no water entry. AARO assesses high confidence of no trans-medium behavior and moderate confidence the objects were sky lanterns. It details thermal crossover and range growth degrading IR discrimination, classic pitfalls. AARO
• AARO “Atmospheric Wakes” (2022–2023) Trails seen behind objects were consistent with video compression artifacts; likely commercial aircraft. AARO

Bottom line: EO/IR often creates the impression of extreme kinematics or trans-medium transitions when range is mis-estimated and contrast collapses. The newer AARO reconstructions show how recovering geometry and environment usually de-anomalizes the scene. AARO

Radar (shipborne/airborne/ground)

Strengths: Range, radial velocity, multi-target tracking, all-weather.
Limitations: Sea clutter, multipath, ducting (anomalous propagation) near maritime temperature inversions, and classification limits for small, low-RCS objects.

• Marine ducting is a common oceanic phenomenon that refracts radar beams, warping apparent target position/velocity and exaggerating or creating returns beyond line-of-sight. Peer-reviewed and Navy-sponsored work documents how ducts alter clutter and track solutions. AGU Publications AMS Confex

These propagation effects complicate any attempt to infer extraordinary performance close to the ocean surface (where sea clutter and evaporation ducting live), precisely where many “trans-medium” stories originate.

Acoustic/Sonar (Undersea)

Strengths: Long-range detection of noisy or cavitating objects; mature signal processing.
Limitations: Publicly released sonar data attached to claimed trans-medium UAP events are scarce to non-existent; most open-source references are anecdotal or secondary.

We therefore cannot draw hard, open-record conclusions about submerged UAP kinematics from acoustics. Absent raw arrays, processing chains, and contextual oceanography, confident claims, either way, remain out of scope for public verification.

Space-based sensors

AARO’s UAP Imagery hub includes space/air cases. Resolved examples trend toward balloons, birds, or artifacts; some remain unresolved for lack of metadata. None of these public cases has validated a space – air – sea seamless transition with multi-sensor corroboration. AARO

The physics: why trans-medium is brutally hard

Crossing from air (ρ≈1.2 kg/m³) to water (ρ≈1000 kg/m³) multiplies dynamic pressure q=12ρV2q = \tfrac12 \rho V^2q=21​ρV2 by ~800× at the same speed. A body at 100 m/s “feels” ~6 kPa in air vs. ~5 MPa (~50 bar) in water, equivalent to ~50 atmospheres, instantly. That pressure spike drives slamming loads, cavity formation, and often structural failure if not managed by geometry and timing.

Water entry and slamming

Peer-reviewed hydrodynamics shows that high-speed water entry triggers transient, nonlinear flows: splash jets, pressure waves, cavity dynamics, and violent slamming whose magnitude depends on entry angle, nose shape, elasticity, and timing. These loads are so severe that a century of naval engineering is devoted to predicting and mitigating them (Wagner theory and successors). Recent literature continues to refine how material flexibility and geometry shape peak forces, none of it suggests effortless, splash-free penetrations at high Mach. Cambridge University Press & Assessment Cambridge University Press & Assessment

Cavitation and supercavitation

In water, drag is crushing unless an object rides inside a vapor cavity. Supercavitation deliberately creates a bubble enveloping the vehicle/projectile to slash skin-friction drag. This is real technology (e.g., supercavitating projectiles and the concept behind high-speed torpedoes). The U.S. Navy partnered on 30×173 mm “Swimmer” ammunition (MK 258 Mod 1) for penetrating the air–water interface and traveling underwater by leveraging supercavitation. That demonstrates the principle, but it does not solve air – water – air vehicle-class transitions. (Nammo GlobalSecurity)

Reality check: Known supercavitating devices either go fast in water inside a cavity or are optimized to punch through a surface skin briefly; they do not cruise like aircraft in air, then plunge into water at comparable speeds, then pop out again with negligible perturbation. Every step (entry, underwater control, exit) is a separate, hard engineering regime.

Case-linked reality checks on claims

The “Aguadilla/Puerto Rico” IR video (2013) Claim: enters/exits water seamlessly

• AARO finding (2025): Two small objects drifting at 8 mph with the wind over land; no water entry. The apparent splitting and disappearance match sensor geometry changes and thermal crossover. Confidence: High that no trans-medium behavior occurred. Attribution: Moderate to sky lanterns. AARO

“GoFast” (2015)  Claim: near-sea-surface, extreme speed; possible sea–air interplay

• AARO finding (2025): 13,000 ft altitude, 5–92 mph intrinsic speed depending on wind alignment; no anomalous performance. Apparent “screaming” low-altitude motion is parallax. AARO

“Triangular” objects and similar imagery

A range of “triangle” or “pyramidal” videos/images have been circulated as evidence of non-conventional craft. AARO’s Southeast Asia Triangles case (2017) used multi-image comparisons and morphology libraries to resolve them as static fishing nets at sea. Lesson: shape alone is wildly unreliable without context and ground truth. AARO

Tying the sensor picture to interface physics

Many trans-medium stories begin with EO/IR imagery near the ocean surface, a domain notorious for:

• Radar ducting & sea clutter  false/warped returns beyond horizon; difficult classification for small targets. AGU Publications AMS Confex 
• IR “thermal crossover”  sensor contrast collapses around dusk/dawn; objects “vanish” without entering water. AARO
• Motion parallax in airborne sensors stationary or slow targets look fast/hard-maneuvering. AARO

To date, no declassified multi-sensor dataset published by AARO/ODNI/NASA demonstrates unambiguous air↔water transition with kinematics that exceed known physics and survive reconstruction.

Known physics vs. claimed capabilities

Hydrodynamics & aerodynamics at the interface

1. Entry/Exit Loads (Slamming): Even carefully shaped wedges experience large, transient pressures; body flex can increase peaks in some regimes. That contradicts “splash-less” high-speed entries unless a cavity is prepared in advance or entry speed/angle is tightly constrained. Cambridge University Press & Assessment
2. Underwater control: Stable supercavitation requires a cavitator and careful pressure and attitude control; steering is hard because control surfaces must remain inside the cavity or interact with its boundary. That’s feasible for small munitions/torpedoes, but no open evidence shows a large craft performing aircraft-like maneuvers underwater.
3. Energy/thermal budget: Generating and maintaining a cavity at high speed while preventing boil-off/shock collapse implies significant power and heat managemen not impossible in principle, but it must leave signatures (acoustic, turbulent wakes, thermal). No public multi-sensor dataset has captured those signatures in a way that compels a trans-medium inference.
4. Exit (water – air): Exiting the water at speed without massive splashback entails precise timing with waves, angle control, and management of cavity closure. Again, no declassified video plus corroborating radar/sonar showing that full envelope exists.

Known tech boundary: We do have supercavitating projectiles and design experience that briefly span air – water. That validates elements of the physics but falls far from the seamless, reversible air↔water vehicle claimed in some narratives. Nammo

Where the government’s latest trend data point

• FY2023 and FY2024 consolidated UAP reports (ODNI/DoD) emphasize more reports, better standardization, and a growing share of cases resolved as balloons, birds, aircraft, drones, or artifacts with a residual under analysis. Those documents expand UAP scope to include trans-medium by definition, but do not verify such vehicles in the public record. AARO
• AARO’s Historical Record Review (2024) a meta-look at legacy programs and claims reported no verifiable evidence of extraterrestrial technology in U.S. holdings, while committing to data-centric case work. U.S. Department of War
• AARO’s case-resolution cards (2023–2025) directly address several incidents once cited for trans-medium features, de-anomalizing them with sensor modeling and environmental reconstructions. AARO

A roadmap for actual testing trans-medium claims

1. Synchronized multi-modal collection: Pair high-frame-rate EO/IR with X-/S-band radar, passive RF, and (for maritime cases) hull-mounted + towed array sonar time-locked with precise platform kinematics and environmental logs (wind, SST, wave spectra, refractivity profiles). This is the minimum to triangulate range/altitude and separate parallax from true motion.
2. Interface-targeted sensing: For alleged entry/exit, instrument with high-speed optical and broadband acoustics to capture slamming signatures, cavitation noise, and splash dynamics. Supercavitation leaves distinctive acoustic and pressure spectra.
3. Open algorithms and reproducibility: Adopt NASA’s recommendations for calibration, metadata, and open repositories; publish raws + code where classification permits so third-party teams can reproduce the chain. NASA Science
4. Environmental disambiguation: Collocate radiosonde/refractivity profiles in maritime operations to constrain ducting models that routinely distort sea-surface radar returns. AGU Publications
5. Null testing: Intentionally collect against known targets (balloons, drones, aircraft, birds) over the ocean surface across ducting regimes to train classifiers and quantify false anomalies.

Implications

For safety and national security

The open record shows real hazards: range fouling, near-misses, and surveillance risks by foreign or commercial systems. Prioritizing multi-sensor logging at ranges, coupled with AARO’s standardization, improves both air safety and counter-intelligence posture. ODNI

For science

Trans-medium claims are an extreme test of our understanding of fluid mechanics, materials, and sensing. If even one verified case passes the data bar, several fields will pivot. NASA’s push for transparent, calibrated datasets is the correct template for that moment. NASA Science

For public understanding

The recent AARO analyses demonstrate that counter-intuitive optics and propagation physics can mimic extraordinary behavior. That does not mean extraordinary behavior is impossible, it means we need the right data to tell the difference, and we must resist inferring kinematics from single-modality clips near the ocean surface.

How to read a “trans-medium” clip responsibly

1. Range solved? Without range you can’t get speed/altitude; ask if range came from stereo, LRF, radar, or reconstructed geometry.
2. Platform motion corrected? If not, parallax is almost guaranteed. AARO
3. Environment logged? Near-surface radar anomalies demand refractivity/duct context; IR oddities near dusk/dawn point to thermal crossover. AGU Publications
4. Water entry/exit signatures? Look for splash kinematics, acoustic spikes, and cavity acoustics, not just pixels.

Bottom line

• Trans-medium is now a tracked category, not a verified capability in public data.
• The most publicized “trans-medium” clips haven’t withstood multi-sensor reconstructions; AARO has repeatedly found non-anomalous explanations (parallax, balloons/birds, thermal crossover, compression artifacts) or left cases unresolved without implying exotic performance. AARO AARO
• Physics is unforgiving at the air–water boundary: unless a system solves slamming, cavity control, underwater steering, energy/thermal budgets, and exit dynamics, seamless trans-medium motion will leave tell-tale signatures. Those signatures are not yet present in declassified, multi-modal datasets.

Research stance: We reject the simplistic claim that “most” UAP are mundane; the residual deserves real science. But on trans-medium specifically, the open record today supports a cautious view: impressive claims, insufficient public evidence. The correct path is data hygiene, reconstructions, and purpose-built collections aimed exactly at the interface where physics turns brutal.

References 

• ODNI Preliminary Assessment: UAP (2021). ODNI
• ODNI 2022 Annual Report on UAP (with AARO); includes Transmedium definition. ODNI
• ODNI/DoD FY2023 and FY2024 consolidated UAP reports. AARO
• AARO Case Resolutions & Official UAP Imagery (GoFast 2025, Puerto Rico 2025, Atmospheric Wakes, etc.). AARO AARO
• NASA UAP Independent Study Team Report (2023). NASA Science
• DoD (2020) press release confirming Navy UAP videos.
• Hydrodynamics & Slamming: Journal of Fluid Mechanics 2023 (water entry loads); Phys. Rev. Fluids 2023 (elasticity & slamming). Cambridge University Press & Assessment
• Radar propagation/ducting over the ocean (AGU 2016; AMS 2010; ONR/NSWC studies). AGU Publications journals.ametsoc.org
• Supercavitation and U.S. Navy MK 258 Mod 1 “Swimmer” ammunition: manufacturer and system references. Nammo
• Marine ducting & radar propagation foundational studies relevant to sea-surface anomalies. AGU Publications AMS Confex

Claims Taxonomy

Verified

• Existence and use of supercavitation for munitions/torpedoes, and air – water penetration by specialized ammunition (e.g., MK 258 Mod 1 “Swimmer”); demonstrates physics of drag reduction and interface penetration. Nammo

Probable

• None in the open record specifically demonstrating seamless air↔water vehicle-class transitions with corroborated multi-sensor data.

Disputed

• 2004–2015 Navy video suite as evidence of trans-medium behavior. Authentic videos (DoD-released) exist, but the public analyses (AARO case cards; NASA notes) show sensor explanations are often sufficient; some events remain unresolved without implying trans-medium. AARO

Legend

• Culture/religion-inflected narratives of sea deities or sky-to-sea chariots are catalogued in anthropology of the sacred; fascinating, but outside evidentiary scope here.

Misidentification

• Puerto Rico/Aguadilla (2013): No water entry; two small objects drifting at wind speed; likely sky lanterns. High confidence of no trans-medium. AARO
• GoFast (2015): Parallax/motion misinterpretation; no anomalous speed, no sea-surface skimming. AARO
• Southeast Asia Triangles (2017): Static fishing nets, not aircraft or craft. AARO

Note: ODNI FY2023 & FY2024 reports acknowledge a residual set of cases under analysis; “unresolved” is not a synonym for “trans-medium.” AARO

Speculation Labels

Hypothesis: If a true trans-medium vehicle exists, it likely exploits controlled supercavitation underwater with on-demand gas generation (e.g., vapor injection), actively managed cavities, and non-traditional control (vectoring jets or magnetic fluid manipulation) while using metamaterial or plasma-based boundary methods in air to suppress shock and thermal signatures.
Researcher Opinion: Such a system would require massive power density and heat rejection plus signature management, observable in multi-domain sensing unless impeccably masked.

Witness Interpretation: Reports emphasizing “no splash” at high approach speeds may be consistent with low-angle grazing entries at modest speeds, optical foreshortening, or IR thermal crossover, each able to erase expected cues in EO/IR at large ranges. AARO

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