After Playa del Carmen, we headed up to Cancun for a few days. From there, we did a guided day trip to the Mayan ruins of Chichen Itza.
The step pyramid, main feature of the complex.
Skull platform, for the display of skulls.
The way the site is designed for acoustics is amazing. For example, someone at the top of the pyramid speaking in a normal voice can be heard by those on the ground.
We also got to stop by Cenote Samaal near Valladolid. It wasn't good for snorkelling like Gran Cenote, but I loved the structure of it - you could lay on your back and look up and see an almost perfect circle, where it had caved in. There was also a platform of about 4m you could jump off, which I did once despite my fear of heights, and it was exhilarating (until I smacked the surface wrong).
We also made a brief stop in the main square of Valladolid, where we had some pretty good churros.
Like Playa del Carmen, Cancun itself wasn't anything special. We stayed in the hotel zone, at an Airbnb, while wishing we could afford an all-inclusive resort. It rained a few times but we went to the beach when we could. I allowed myself to be dragged out at night once, to Coco Bongo, which was average (I generally dislike nightclubs).