Riihahti was sunk in an engagement with Soviet motor torpedo boats on 23 August 1943.

[a] By the late-1930s, the Finnish Navy was focused on defence of the nation and the only ships under construction by Finland were the Ruotsinsalmi-class minelayers and assorted smaller craft.

[3][b] The vessels were powered by two Rateau diesel engines turning two shafts creating 890 kilowatts (1,200 bhp) and giving the minelayers a maximum speed of 15 knots (28 km/h; 17 mph).

Though not designed for anti-submarine warfare, the Ruotsinsalmi-class ships mounted two depth charge racks and two throwers.

[7] In July 1943, Soviet forces attempted a breakout into the Baltic Sea from where the Finns had them blockaded via the Seeigel-Rukajärvi mine barrage.