The Commander Islands archipelago consists of 15 islands of different size from 1667 km2 to less than 0.5 km2 which are crowns of a huge submarine volcanic ridge extending from Alaska to Kamchatka. The most ancient Commander structures are dated as the beginning of Paleogene (60-70 million years ago). Now low hills and coniform mountains occupy the most part of the Islands' territory. The highest point of the largest Bering Island is the Steller peak (755 m). The most part of river valleys (except the greatest ones - as a rule formed along fractures) is cut short by a coastal scarp forming picturesque waterfalls 10 - 100 meters high.
Climate is characterized by mild winter (- 4°C in February) and cool summer (+ 10.5°C in August) with short intermediate seasons; low precipitation, constantly high relative humidity of air and strong winds
The Commander elevation shelf and continental slope are characterized with very abrupt depth: in the limits of 30 miles from the shores all the depth diapason can be observed – from littoral to ultraabyssal. It could be mentioned that about 1,000 macrobenthic species inhabit the most studied shallow shelf zone (up to the depth of 40m) only.
As for inland waters the two large islands have well-developed drainage network with one navigable river, and Toporkov and Ariy Kamen' are absolutely devoid of fresh water.
According to the last data, 389 species of vascular plants have been registered in the Commander Islands' flora, relating to 183 genera and 63 families. In the system of floristic zoning the Commander Islands are related to the Commander-Aleut region of Kamchatka province of Boreal floristic area.
There are 203 bird species registered on the Commanders according to the last data, including 58 nesting ones. There is a number of endemic forms and it is the only place in Russia where a number of American birds are regularly reproducing.
Fauna of the marine mammals is extraordinary diverse. 32 species of 13 families and 4 orders has been registered there. About 50% of marine mammal fauna representatives are regarded as rare and needing special protection: 12 species are enlisted into the IUCN Red List and another 2 species - into the Red Book of Russia.
Arctic fox is the only aboriginal species of terrestrial mammals inhabiting the Commander Islands. There are two relict endemic Arctic fox sub-species: Bering Arctic fox - Alopex lagopus beringensis and Medny one -A. I. semenovi, differing not only by their outward appearance, but also by some ecological and morphological features.
According to preliminary data, the fish fauna of the Commander underwater plateau includes 216 species and subspecies, representing 148 genera, 56 families and 20 orders.