Until 2008, only Finnish citizens were authorised to act as the master of a Finnish merchant ship. Since then, Finnish and EU/EEA citizens may act as the master of a Finnish merchant ship.
"Chapter 6 - Master of the vessel
Section 1 - Nationality of master:
Only a citizen of a Member State of the European Union or a state belonging to the European Economic Area may act as the master of a Finnish merchant ship."
(Maritime Act (674/1994), as amended by Acts 310/2008 and 1688/2009, Chapter 6, Section 1 [google translation])
Maritime Act (674/1994), Chapter 6, Section 1
[<a href="https://www.finlex.fi/fi/laki/ajantasa/1994/19940674">Act</a>]