Danish defence software at the heart of international subsea security exercise

Defence forces, police and companies from five countries have spent two weeks in the Baltic Sea practising protecting undersea cables, offshore energy sites and ports — with Danish software at the heart of the operation.

Today, SeaSEC Data2Sea 2026 comes to a close. For two weeks, teams from Denmark, Germany, the Netherlands, Norway, and Sweden have been gathered off the coast of Rostock, testing how quickly they can spot, make sense of and respond to threats against the infrastructure that keeps northern Europe's lights on and its data flowing. At the centre of it all was SitaWare Maritime, a system built by Danish firm Systematic that pulls together information from ships, sensors and agencies into a single, shared picture of what is happening at sea.

The scenarios were designed to feel real, and participants faced multiple threats unfolding at the same time, without knowing in advance what would happen or when. Lasse Krabbesmark, a former Danish naval officer who now works as a product manager at Systematic, participated in the exercise:

"We practised three different scenarios. One involved protecting a power cable on the seabed. The teams had to pick up suspicious activity, track it and report it before the situation escalated. They didn’t know what's coming or exactly when — so it was about as realistic as it gets," he explains.

Systems put to the test in real-world conditions

The remaining scenarios dealt with defending an offshore platform and securing a port against intrusion. It is exactly these kinds of fast-moving, multi-layered situations that put the greatest strain on people, technology and communication.

"What this exercise really tests is whether everyone involved can piece together a clear picture quickly enough to act when things start going wrong. You only find out whether the information, the coordination and the communication actually work when you're under pressure and the decisions matter," Krabbesmark says.

Germany, the host nation, already uses SitaWare Maritime in its own operations, so the exercise doubles as a test of how well the system works alongside the ships, units and agencies that would be called on in a real incident.

A security challenge for Europe

Protecting what lies beneath the sea has become one of Europe's most urgent security challenges. Power cables, data links, ports and offshore installations are part of the backbone of modern life — and that makes them targets.

Krabbesmark was glad to see the software put through its paces in a lifelike setting.

"Maritime security is increasingly about joining up what different people see, what they plan to do and how they respond — across organisations and across borders. When things happen above, on and below the surface at the same time, everyone needs to be looking at the same picture," he says.

SeaSEC Data2Sea 2026, which ran from 13 to 24 April 2026, has been a practical test of how ready Europe is to protect critical infrastructure at sea, in an environment where threats can appear suddenly and from several directions at once. Danish software has played a central role in that test.