Abstract <p>Fluctuations in the level of the Caspian Sea are multiscale. Based on an analysis of transgressions (the results of hydrometeorological measurements, as well as paleodata, the reconstructions of which are much more reliable than regressions), it was established that, in the range of 10⁰–10⁵ years, sea level fluctuations are self-similar with a Hurst coefficient <i>H</i> ~ 1/2, which is a sign of a random process such as a Brownian movement. It is assumed that the sources of such a large set of oscillations of various scales are the Milankovitch mechanism in the long-period region and the mechanism of atmospheric baroclinic instability in the short-period region.</p>