Kolmikulma (Swedish: Trekanten; literally meaning "Triangle"), also known as the Diana Park,[1] is a small, rectangular triangular-shaped park located in the Kaartinkaupunki district in the city center of Helsinki, Finland.

The triangular nature of the park is due to its location on the border of two grid pattern areas in different directions.

For a long time, the National Board of Customs operated in the house north of the park.

In 2008–2012, there was also the end of tram line 9 leading to East Pasila at the edge of the park.

Another of the starting points of the Crown Bridges tram connection to the center of Helsinki is planned for Kolmikulma.