The Secchi disk depth is one of the most important physical indicators of the water clarity. When studying Lake Baikal with the surface area of 31,722 sq. km, remote sensing is a necessary tool to assess the Secchi disk depth within the entire lake. To develop regional algorithms for estimating the Secchi disk depth in Lake Baikal is based on the use of a set of coincident AVHRR data and in situ Secchi disk depth measurements. Because of research, the linear algorithm for the periods from the beginning of June to mid-July and from midSeptember to the end of October and the nonlinear algorithm for the period from mid-July to mid-September with the root-mean-square error of 1.9 and 0.9 meters respectively were developed. A series of maps of the distribution of the Secchi disk depth in Lake Baikal for the ice-free period of different years was created using the AVHRR-based regional algorithms.