Cuautla sits atop a network of geothermal springs that have been used since pre-Columbian times, and the balnearios — large outdoor bathing complexes built around them — are the reason most visitors come. Los Limones is among the most popular, with pools of varying temperatures fed by sulphurous warm water. The smell hits you before you see the water. You either get used to it in five minutes or you don't, but the warmth is genuinely pleasant, especially after a long drive.
Weekends bring day-trippers from Mexico City in volume, and the balnearios become full family affairs — kids in floaties, food stalls along the perimeter, and a general holiday atmosphere. If you want the experience without the crowd, come on a weekday morning. The springs don't care what day it is.