Castricum is a municipality and a town in the province of North Holland in the Netherlands.

North Holland is a province of the Netherlands in the northwestern part of the country. It is located on the North Sea, north of South Holland and Utrecht, and west of Friesland and Flevoland. As of January 2023, it had a population of about 2,952,000 and a total area of 4,092 km2 (1,580 sq mi), of which 1,429 km2 (552 sq mi) is water.