The Kostroman navy was the space defense force of the Commonwealth of Kostroma.

It was small compared to the fleets of the Republic of Cinnabar and the Alliance of Free Stars, and was also not very efficient, as the Commonwealth's merchant fleet took the greater and better trained part of the personnel. Ratings in the navy were mostly foreigners, while the officer ranks were filld with men who preferred to stay home rather than go spacing; as a result, the ships spent sealed in the Navy Pool.1:1

The corvette Princess Cecile was originally in Kostroman service before she was seized by RCN personnel under Lieutenant Daniel Leary and later bought into Cinnabar service.1:3