We present in depth data of the sea urchin population in the Arctic Porsangerfjord. Sea urchins were collected by hand from randomly chosen square meters of two present habitats: a sea urchin barren, characterized by stony ground without major algae growth, and the neighbouring kelp forest with a healthy macroalgae community. Both habitats are located near the shoreline of a bay in the Porsangerfjord, called the Holmfjord, and sampling took place in less than 1 m depth at low tide. Sampling was conducted in two consecutive years, summer 2022 and summer 2023. Data collected from the sea urchins includes the test-diameter, freshmass, species and morphotype.