In this paper we discuss the best Siberian permafrost analog of the Martian cryosphere in connection with the design of deep-sounding geophysical methods for the detection of liquid water beneath frozen formations on Mars. The peculiarities of the terrestrial cryolithozone and its unique thickness (up to 1.5 km) in the region under consideration (Western Yakutia) are described. The Russian experience in detecting the lower boundary of permafrost, by various geophysical methods, and suggestions regarding the most effective methods for the deep sounding of the Martian cryosphere are also briefly discussed.