One of the unique site of Sakhalin — the mud volcano — is located virtually within a walking distance from Yuzhno-Sakhalinsk and acts as an attraction point for both amateur tourist groups and organized excursions.
According to the geographic reference book, mud volcanos are usually attached to either oil-and-gas bearing deposits, or the areas of “common” volcanos. The largest and most typical mud volcanos in Russia are concentrated in two regions: on Taman Peninsula and on Sakhalin Island. Abroad, there are mud volcanos in Azerbaijan, Spain, Italy, New Zealand, and Central America. Mud volcanism is a very interesting phenomenon that is closely related to the tectonic activity and oil-and-gas bearing capacity of the earth’s depths. The mechanism of such volcanos’ formation is still not quite clear to the scientists. The total number of known mud volcanos on Earth exceeds 700. In the oil-and-gas bearing areas, mud volcanos exude methane and, to a lesser degree, carbon dioxide, or, sometimes, carbon monoxide and nitrogen. Their waters contain bromine, iodide and boron, thus making it possible to use the mud for therapeutic purposes.
On Sakhalin, mud volcanoes are recorded to be present in four locations: in the outskirts of Yuzhno-Sakhalinsk, near Pugachyovo settlement, in Lesnoy settlement, and near the Dagi Gulf in the north of Sakhalin, 30 km to the north from Nogliki urban-type settlement.
Yuzhno-Sakhalinsk mud volcano is located 18 km to the north-west from the region’s center. It is a preferential protected natural area and a natural monument of a regional significance. The natural monument is a mud volcano field — specifically, a flat emission cone of the products of eruption of methane gas, carbon dioxide and water with a slight show of oil. The field has a nearly round shape about 200 m in diameter.