Lake Tuusula or Lake Tuusulanjärvi is a lake on the border of the municipalities of Tuusula and Järvenpää in Southern Finland. The lake has an area of 6.0 square kilometres. Since the beginning of the twentieth century the shores of Lake Tuusula has been an artist's colony. The houses of Aino and Jean Sibelius, Juhani Aho, Pekka Halonen, Eero Järnefelt, Joonas Kokkonen and Aleksis Kivi are on the edges of the lake.