Culture
Instead of all the wonders under the water Mexico has plenty of culture to offer.
Visit the temples on the Maya route like Chitchén Itzá and Uxmal, go to the ruins of the beautiful Palenque in the middle of the jungle or visit Tulum situated on the rocks overlooking the caribbean sea.
If you want we can make a daytrip to the ruins of Tulum, combined with a dive in one of the cenotes.