From 1909 to 1911, Kirchner and other members of the German Expressionist group Die Brücke spent part of each summer at the Moritzburg Lakes near Dresden. Bathers have been used on countless occasions throughout European art history and was particularly common during the Impressionist movement. If you look at this painting and see the reminiscences of Cezanne's paintings, you're right. Here Kirchner represented both genders (which wasn't that common in the past), meaning the innocence of other bather paintings is not found here. The relaxed, communal lifestyle and nude bathing reflected a cult of nature that was growing in Germany at the time. The exaggerated colors in this painting so typical for the Expressionists emphasize the nudity of the figures. The original effect, however, may have been too extreme, as Kirchner repainted parts of the picture in 1926, making the colors lighter and the surface of the painting more even.