During Donsö Shipping Meet in September 2025, one of the most extensive total defence exercises for Swedish shipping in modern times was conducted. How well did it work? A new report from Lighthouse shows that the exercise strengthened preparedness, but also highlights clear areas for improvement.

On 1 September 2025, the Total Defence Exercise DSM 2025 was carried out on and around Donsö in the southern archipelago of Gothenburg. The exercise brought together authorities and private actors to, for the first time, jointly test how critical societal transport functions operate under difficult and demanding conditions. A total of 230 participants from shipping companies, authorities, the military, and the port sector took part.

The exercise was based on six scenarios set during a state of highest alert—that is, a wartime situation. Each scenario was practiced both theoretically and practically in two separate components, without direct links between them.

The theoretical component, a so-called tabletop exercise, was held at the Mission Church on Donsö and focused on decision-making processes (who makes decisions, in what order, and with what reasoning) without implementing them in practice.

The practical component, called “vessel,” consisted of hands-on exercises carried out onboard real ships and in bridge simulators. Participants were confronted with situations such as groundings, mine threats, military escort, radio-silent navigation, and not least how to respond when discovering hostile individuals onboard and needing assistance from special forces.

“This is where they practiced working together. It’s not just about special forces being able to board—they also need to navigate an unfamiliar vessel and secure it,” says Anna Hedén of RISE, one of the authors of the Lighthouse report Lessons from Exercises in Maritime Total Defence (LÖST), which evaluates the practical component of the exercise.

The study behind the report is based on data collection and observations before, during, and after the exercise, document studies, interviews with participants, and a survey.

“The exercise itself lasted an afternoon, but much of the knowledge generated came from the work before and after. There has been remarkable engagement from authorities, the Armed Forces, shipping companies, ports, and subcontractors. Everyone has considered it important to train together.”

The report also shows that participants generally found the exercise valuable for building connections, that its lessons are “practically applicable,” and that it has strengthened Sweden’s total defence. The realization that “we can handle this” is an important outcome, according to Anna Hedén.

“The main conclusion is that shipping functions well in these contexts. This is largely due to established routines for proactive bridge team operations, which ensure good navigational performance. However, certain aspects can be tricky—such as silent navigation, meaning no signals can be transmitted. You operate without radar, radio communication, and with lights turned off. Everything relies on visual assessment, which is not something crews are used to. That became very clear.”

At the same time, several challenges were identified. Time discipline proved to be a critical factor. Since the exercise was limited to one afternoon, time pressure meant some activities had to be cut short to make room for others. The report concludes that fewer exercises carried through to completion provide better learning than many interrupted ones.

“Because there was no communication between the command exercise and the practical component, the vessels were not responding to direct orders. This made the practical exercises somewhat too controlled. The crews were not stressed by uncertainty. While such stress shouldn’t be created in real shipping lanes, simulators could allow for more complexity,” says Anna Hedén.

Looking ahead, the report calls for more advanced exercises with higher intensity, greater uncertainty, and a clearer focus on operational decision-making—particularly for shipmasters.

The report also presents a list of smaller measures aimed at different stakeholders, ranging from replacing outdated forms to developing or revising manuals, regulations, instructions, and relevant frameworks.

A follow-up total defence exercise is planned for Donsö Shipping Meet 2027.

The report Lessons from Exercises in Maritime Total Defence (LÖST) was authored by:
Hanna Varvne, Anna Hedén, and Sara Rogerson at RISE
In collaboration with:
Jonas Flodén, Victor Eriksson, and Johan Woxenius (University of Gothenburg)
Staffan Bram, Mikael Hägg, and Åsa Kärnebro (RISE)