In this paper we discuss the dynamic response to mountain breeze circulation in Alchichica, a deep crater lake in Mexico. A numerical model was used to simulate integrated drift currents based on wind data sampled at 1-h intervals. The results are compared with those measured by an ADCP. Measurements taken with a level recorder demonstrate that the mountain breeze is coordinated with diurnal level inclinations up to 11 cm and that it simulates free seiches with a period of 2.7 and 2.1 min with amplitudes equal to 7 mm and 4 mm. Measurements carried out with a SBE-19 profiler show that in the second half of day the breeze blowing from the north causes a sinking of the thermocline by 3 meters in the southern part of the lake. It appears that periodic inclinations of the thermocline serve as the main mechanism in the generation of internal waves in Lake Alchichica.