So, Swedish marines doesn't have a motto, but something our officers would always say, to the point where it was almost a de facto motto was "solen skiner alltid på en kustartillerist (ambifiesoldat). (the sun always shine on a Marine).
Google translate seems to have problems with the word "marinsoldat" (marine soldier) so I tried sea soldier. Since I don't speak latin I don't know how correct this is, but here we go. Latin speakers feel free to correct.

Sol lucet mare militem semper