Abstract <p>The formation of the active layer on Eurasian Arctic islands is controlled by climatic zonality. The thickness of the active layer in the southern region of the Atlantic climatic province may exceed 1.5 m due to the effect of warm atmospheric and oceanic masses coming from the Atlantic region. The background thickness of the active layer decreases to approximately 1 m in the northern and eastern regions of the Atlantic climatic province. The seasonal thawing in the Siberian climatic province is minimal and varies within 0.3–0.8 m. Further to the east, in the Pacific climatic province, the background active layer thicknesses slightly increases up to about 0.8 m on Wrangel Island due to the warming effect of Pacific masses. With equal average annual air temperatures in continental regions and on Arctic islands, the active layer thickness on Arctic islands would be lower because of stronger cooling in winter under conditions of a dense thin snow cover and a shorter and colder summer.</p>