Ruotsinsalmi sea Fortress

Ruotsinsalmi sea Fortress is a fortification system spanning multiple islands with several connected defensive structures built from stone. The complex contains preserved gun stations and original towers that once formed an integrated coastal defense network.

Construction began in 1791 as a response to a war between neighboring powers that created a need for stronger coastal protection. The project was completed over several decades as military planners expanded the fortified positions.

The fortress system emerged after conflict between neighboring powers and reflects how coastal defenses were designed during that era. These connected forts worked together to monitor ships and control the waters around them.

The islands are accessible by boat, and you can walk through the stone fortifications and explore the structures directly. Wear comfortable shoes since the terrain is uneven and some areas are open to the elements.

The fortress used sunken barriers below the water surface between islands to slow down ships trying to pass through. This underwater defense method was an innovative way to stop attackers without obvious obstacles above the waves.

Location: Kotka

Part of: South-Eastern Finland fortification system

GPS coordinates: 60.44167,26.97111

Latest update: December 8, 2025 21:02