In the early 1980s, the Finnish National Board of Navigation began looking for a replacement for the aging Karhu-class icebreakers Karhu, Murtaja and Sampo which had been built in the late 1950s and were no longer wide enough to escort modern merchant ships.

[5] The development of the new class of icebreakers, dubbed Karhu II in the preliminary papers, intensified when Wärtsilä opened a new ice model test facility in 1983.

However, the strength of the new icebreaker was put to the ultimate test when she encountered a large pressure ridge reaching all the way to the seafloor some 20 metres (66 ft) below the surface.

Since the new icebreaker had a smooth inclined stem and lacked the bow propellers of her predecessors, she rode up the ridge and began listing to the port side as the hull rose from the water.

[3][13] Furthermore, the traditional colours dating back to the Imperial Russian era, yellow and black, were replaced with the colors of the flag of Finland, blue and white.

Due to the extensive use of advanced automation, which allowed everything ranging from starting and stopping the main engines to raising and lowering the flag to be done remotely from the bridge, Otso had the smallest crew among Finnish state-owned icebreakers when she entered service in 1986.

[13] While Otso holds the highest Finnish-Swedish ice class, 1A Super,[2] it has hardly any meaning for icebreakers which are of considerably stronger build than merchant ships operating in their care.

Her main generators, four 16-cylinder Wärtsilä Vasa 16V32 four-stroke medium-speed diesel engines producing 5,460 kW each and driving 7,540 kVA Kymi-Strömberg alternators, are located on the upper deck beneath the helicopter platform.

[13] The uncommon location of the engine room was chosen to improve the seakeeping characteristics of the icebreaker by moving the center of gravity higher to calm the ship's motions in heavy weather.

Although it would have been possible to use two smaller DC motors in tandem, recent advances in drive and control technology as well as excellent experiences from a prototype installation on board the Finnish research vessel Aranda were in favor of the new type of propulsion system.

In addition, she has large ballast tanks and high-capacity pumps that can be used for rapid heeling and trimming to release the icebreaker if she is immobilized by compressive pack ice.

However, after the early teething problems and successful ice trials, the opinions changed and the performance of the "Bubbler of the Bothnian Bay" was generally deemed to be satisfactory.