Tl in the name means the former province of Turku and Pori (Finnish: Turun ja Porin lääni).

Koski's neighbouring municipalities are Loimaa, Marttila, Pöytyä, Salo, Somero and Ypäjä.

The church of Koski was designed by architect Toivo Paatela and it was completed in 1935.

There is also an observation tower near the highest points of Hevonlinna ridge and Hevonlinnanjärvi.

[citation needed] Media related to Koski Tl at Wikimedia Commons This Western Finland location article is a stub.