Mustasaari
Mustasaari is a Finnish surname of toponymic origin, meaning "black island". It is most commonly found in the western parts of Finland, particularly in the Ostrobothnia region. The name likely originated from individuals who lived on or were associated with an island that was historically described as "black," possibly due to vegetation, soil color, or its appearance from a distance. As with many Finnish surnames, it became established through inheritance, passed down from father to son.
The prevalence of the Mustasaari surname is tied to historical land ownership and settlement patterns in Finland.