The Swedish Navy at the eve of the Great War was the most powerful in Scandinavia, after the German Imperial and Russian Imperial Navies.
Despite strong incentives and pressures from the central powers, Sweden stayed neutral all along the war, exporting its iron ore to both belligerent sides. Sweden also had a powerful coastal fleet in addition to submersibles, torpedo boats and mine warfare, some of which were recent and almost pocket dreadnoughts like the Sverige and Oscar II. Both were also well suited for shallow waters and archipelago of this area. They entered indeed in calculations on both sides, allies and Germans alike.
The only naval military intervention of Sweden was to secure the Åland Islands in February 1918, with a naval-backed occupation until April, before the Islands were ceded to the newly-independent Finns. During WW1 Sweden could enforce its neutrality policies with a force of 12 Coastal Battleships (three in construction), 10 Monitors, 7 Cruisers, 8 Destroyers, 49 Torpedo Boats, 8 Submersibles, and 9 auxiliary ships like minesweepers and minelayers.
Since this is an important fleet the current page and fleet review will be completed and released in two parts. Here is the first one, about Swedish coastal battleships.