In the course of the 2019−2020 round-the-world expedition of the oceanographic research vessel Admiral Vladimirskii, which repeated the route of F. Bellingshausen and M. Lazarev in 1820, a large volume of magnetic data was obtained, including the data about the Antarctica area. One of the purposes of the performed investigation was to determine the position of the South magnetic pole from experimental data. This was the reason to revisit the data on the declination, which were obtained during the Bellingshausen expedition, and determine the position of the South magnetic pole from those data. In the first part of the present paper, to solve this problem, we propose and realize several methods, which were preliminarily tested on model examples. In the second part, the position of the South magnetic pole is determined from the data on the measurements of the magnitude and components of the magnetic field carried out onboard the oceanographic research vessel Admiral Vladimirskii.