SUBMERSE’s audacious plan to turn the world’s seabed cables into a shared instrument, while governments race to keep their secrets hidden
In the deep oceans, where visibility fades into pitch‑black pressure plains, a new kind of sensing revolution is quietly taking shape. It does not rely on satellites, radar, or submarines. Instead, it exploits something already there, thread‑thin strands of glass and plastic carrying the world’s internet traffic. These fibre‑optic cables, long treated simply as pipelines for data, are being reimagined as a vast, distributed scientific instrument. With the right technology, they can detect earthquakes, map ocean currents, track whale migrations, listen for underwater explosions, and monitor vessels that would prefer to remain unseen.
This is the world of Fiber Optic Sensing (FOS), and Europe’s SUBMERSE project has become the most ambitious attempt yet to harness it. But the project’s biggest discovery may have little to do with seismology or oceanography. Instead, it has exposed a fundamental geopolitical tension: the same technology that can detect tsunamis is also capable of tracking military submarines. And the same algorithms that reveal the behaviour of whales can identify ships engaged in illegal or covert operations.
Science and national security are becoming inseparable. The question now is whether they can coexist.
The Global Rise of a Dual‑Use Technology
Fiber‑optic sensing is not new, but its applications have expanded at a speed that few anticipated. Traditionally used in industrial settings—monitoring pipelines, detecting strain on bridges—FOS is now being deployed across the seafloor. These optical fibres are so sensitive that slight temperature changes, pressure shifts, and tiny acoustic vibrations alter the light traveling inside them. Interrogators—specialized instruments—can detect these distortions and translate them into signals.
The result is a continuous stream of real‑time information that reveals earthquakes, volcanic rumblings, wave energy, seafloor movement, and the presence of vessels.
But there is a catch: the volume is astronomical.
One interrogator can produce 3–7 terabytes of raw data every day, most of it unusable noise unless processed instantly. And buried within that noise are signals governments view as highly sensitive: submarine passages, military vessel manoeuvres, intrusions near pipelines or power cables, and the distinctive acoustic fingerprints of ships of strategic interest.
The data is scientifically invaluable, and politically radioactive.
SUBMERSE, backed by European partners, set out to unlock this potential. Yet it quickly discovered that “open science” and “national security” are not merely different goals, they are often fundamentally at odds.
Europe’s High‑Stakes Experiment
The SUBMERSE project aims to build a distributed research instrument that streams data to seismologists, oceanographers, ecologists, and many other scientific communities. But as the project advanced, its partners ran into a thorny problem: many governments do not want raw FOS data leaving their borders, let alone entering open scientific repositories.
Researchers want transparency. Agencies want secrecy.
At a 2024 consortium meeting, SUBMERSE partners reached a pivotal realization: rather than treating security agencies as a barrier, the project needed to treat them as collaborators.
The white paper argues that security services and researchers actually share a mutual interest in the development of FOS, both rely on improved detection, better algorithms, and more comprehensive monitoring networks. The relationship is not adversarial but symbiotic.
From this insight emerged the project’s central architectural proposal: a Trusted Research Environment (TRE)designed specifically for FOS.
How Fiber‑Optic Sensing Works
FOS uses the fibre‑optic cables that already span Earth’s oceans.
When a laser is sent down the fibre, environmental changes—pressure, temperature, strain—alter the light’s behaviour. These distortions are detectable.
Two key technologies:
1. Distributed Acoustic Sensing (DAS)
- Uses backscattered laser light
- Detects vibrations (earthquakes, ships, whale calls)
- Very high data volume
2. State of Polarisation (SoP) sensing
- Tracks polarization changes of light
- Highly sensitive to temperature and slow strain
Every acoustic or physical event creates a unique “fingerprint.”
Machine learning models are now being developed to identify and classify these fingerprints—everything from tsunamis to trawling vessels.
AI at the Centre of the Seabed Race – Event Fingerprinting
Artificial Intelligence is essential to FOS. With human analysts unable to handle terabytes per day, ML and deep‑learning models are being trained to:
- detect event signatures
- classify vessel types
- distinguish natural vs. human‑made events
- identify anomalies in near‑real time
But AI introduces new dangers:
Models trained on sensitive military signatures could reveal intelligence inadvertently. A poorly secured dataset could expose the exact frequencies associated with submarine movement. Even metadata, like the timing of blackout periods, could signal when agencies are conducting operations.
The white paper makes a sobering point: we barely understand the full sensitivity of FOS data, and therefore cannot yet predict all the ways it may be exploited.
The Security Paradox
Governments see FOS as a double‑edged sword.
On one hand, it provides:
- early warning for earthquakes and tsunamis
- monitoring for sabotage attempts on pipelines and cables
- real‑time tracking of illegal maritime activity
- access to sensitive signals otherwise invisible to satellites
On the other hand, sharing these signals might reveal:
- submarine routes
- naval operations
- behaviour of classified vessels
- intelligence vulnerabilities
- patterns of military readiness
The result is a paradox:
Science requires openness; security requires constraint.
The SUBMERSE white paper argues that these interests are interdependent: science cannot progress without agency cooperation, and agencies cannot afford to ignore a technology that dramatically enhances situational awareness.
A New Strategic Domain Beneath the Seas
The political implications are enormous.
1. U.S. and Canada already run restricted FOS systems
The white paper details how Ocean Networks Canada and the U.S. Navy use diversion servers and filtering systems to keep sensitive acoustic data behind military firewalls. This model, however, limits scientific access.
2. Europe is fragmented
Unlike the U.S., Europe lacks unified command structures, budgets, and legislative frameworks. Each state treats subsea surveillance differently, making continent‑wide collaboration difficult.
3. Hybrid warfare is rising
Attacks on subsea pipelines and cables in recent years have forced NATO and EU defence agencies to recognize the seabed as a new frontier of conflict. FOS provides rare visibility into this murky domain.
4. China’s subsea strategy
Although not addressed in the white paper, the implications are clear: any global power with access to fibre sensing could monitor strategic waterways without deploying naval assets.
If shared widely, FOS data becomes a diplomatic minefield. If hoarded, scientific potential evaporates.
SUBMERSE’s Proposal for Peace
SUBMERSE’s most important contribution may not be technological, but organizational: a
framework for co‑governed, transparent, rule‑based data handling.
Key features:
- Raw data enters a secure HPC facility
- Agencies can apply filters (time deletion, frequency removal, spatial excisions)
- Only vetted researchers access raw data
- Non‑sensitive streams (Exit Data B) are released publicly
- Agency‑only data (Exit Data C) never leaves
- FAIR data standards govern scientific outputs
- Automated and manual review options exist for sensitive events
In SUBMERSE’s vision, this TRE becomes the “production line” for global subsea analytics.
Risks and Ethical Concerns
The white paper implicitly raises several pressing issues:
1. Surveillance creep
Once governments realize they can track any vessel near a fibre cable, oversight will be essential.
2. Scientific distortion
If agencies over‑filter data, scientific results may become incomplete or misleading.
3. Data deletion risks
FOS data cannot be stored indefinitely. Without careful governance, critical signals may be lost forever.
4. International inequity
Nations without FOS access may face strategic disadvantage.
5. Misuse of AI
Models trained on filtered data may make faulty assumptions, with consequences for hazard prediction and security analytics.
Recommendations for Policymakers
1. Establish national FOS governance frameworks
Every state hosting landing stations should define clear rules.
2. Create multilateral subsea monitoring agreements
To avoid geopolitical suspicion, NATO, the EU, and partners in the Indo‑Pacific should explore transparent collaboration.
3. Mandate TRE‑style architectures
FOS data handling must be secure, auditable, and fair.
4. Fund AI‑based fingerprinting openly and cooperatively
Shared models will reduce fragmentation and increase safety.
5. Promote limited, controlled access for vetted researchers
Scientific progress depends on responsible openness.
6. Address legal and ethical gaps
Existing laws on data privacy, critical infrastructure, and surveillance do not cover FOS adequately.
A Seabed Future in the Balance
Fiber‑optic sensing is transforming the oceans into a living observatory. But its power cuts both ways. It can detect earthquakes and intruders, protect seabed infrastructure or expose military secrets, accelerate science or exacerbate geopolitical distrust.
SUBMERSE argues that coexistence is possible, but only if governments and researchers forge binding, transparent partnerships. Without such a framework, the world risks losing not only scientific opportunities, but also the chance to build a cooperative global system for seabed security.
FOS technology is no longer just a scientific tool. It is a strategic asset.
And the race to control it has only just begun.
References
European Future Innovation System Centre. (2025). Fibre Optic Sensing Security Architecture: SUBMERSE White Paper. SUBMERSE Project, Grant Agreement No. 101095055. Danish e‑Infrastructure Consortium (DeiC), NORDUnet, GFZ, GÉANT.
