Various geologic data suggest that Lake Chichoj stretches above of a body of gypsum well exposed on outcrops farther west. There, gypsum dissolution is responsible for repeated mountain flank collapses in the valley of Los Chorros. The lake occupies at least three coalescing dolines likely formed by dissolution of gypsum at depth.  The dolines are probably only a few tens of thousands of years old, and the marshlands that surround the lake are likely covering similar, sediment-filled dolines. They are therefore susceptible to resumption of ground subsidence, if gypsum keeps dissolving at depth. The new phase of subsidence could either be slow and continuous, or pulsed, and possibly fast, even instantaneous. It is even possible that the marshes are actively subsiding, since no monitoring of subsidence has ever been undertaken. Subsidence might also be occurring under the combined effect of slow sediment compaction and oxidation/decomposition of the organic matter trapped in the sediments. The accommodation space created by the subsidence would be filled by mineral and organic sediments over the marshlands.