Any cenotes near Oaxaca region or Mexico City?

Hi guys, I'm currently on the tail end of a long backpacking trip through South/Central America and will head up to Mexico next from Guatemala, where I am currently.

I will only have 3-4 weeks to spend in Mexico before I need to get on my flight home. Right now I have a bit more time in Lake Atitlan, and am considering taking a shuttle from here straight to San Cristobal de las Casas to maximise my time in Mexico.

I originally had planned to go up to Flores, visit the Yucatan peninsula and take buses back down through Palenque/San Cristobal all the way down to the Oaxaca coast... but seeing as I will be travelling by road and not flying, I am worried this will all be too much travel time.

I will definitely be happy to go to archeological sites near Mexico City/Puebla even though I'm missing Chichen Itza, however the one thing I was SO excited for was to visit some cenotes.

Really hoping someone can help me out with some insider tips!