Zaratamo is a town and municipality in the province of Biscay, within the autonomous community of the Basque Country in northern Spain. It covers an area of 10.2 square kilometres and sits at an elevation of 173 metres.
As of 2019, the municipality had a population of 1,614, giving it a population density of 158.8 people per square kilometre. The population is almost evenly divided by sex, with 50.1% female and 49.9% male residents.