I booked a couple of all-day tours with MexicoKan. My first tour, Mayan Inland Expedition, was my favorite. We were driven deep into the state of Quintana Roo to the ancient Mayan city of Cobá, once the most powerful city in the region. Massive pyramids and monuments had been buried in the jungle for over a thousand years, only recently discovered by archaeologists. Lush vegetation still covers most of the city, and it’s exciting to see only half-excavated ruins emerging from the vines and tree roots.

I biked through Cobá, climbed the pyramid of Ixmoja, ziplined across a turquoise lake in the Punta Laguna nature reserve, and made fresh tortillas for our homecooked lunch with a local family.

Our last activity on this tour was swimming in a cenote that we had all to ourselves. A cenote is a deep, water-filled sinkhole in limestone created when the roof of an underground cavern collapses. This creates a natural pool which is then filled by rain and water flowing from underground rivers. The water in these cenotes is crystal-clear, calcium-rich freshwater. The calcium levels are so high, in fact, that it’s hard to tread the water; I had to wear a lifejacket because my arms were getting so tired! The Yucatán Peninsula has thousands of these cenotes because the ground is primarily made up of porous limestone. Cenotes were the area's main source of water and played an important role in ancient Mayan civilization, as passages to the underworld and sites for sacrificial purposes.

The next day, I had another tour with the same company. We started off at Chichen Itza, with the iconic, wonderfully symmetrical pyramid, Temple of Kukulkan.

Nearby is the Great Ball Court, the largest and best preserved ball court in ancient Mesoamerica. This sport was played throughout the Mayan civilization, and also functioned as a sacrificial and religious event. The winning team’s captain was decapitated — an honorable sacrifice to the gods. A rubber ball could be hit with the right hip, right elbow, and right knee, but no hands. The aim was to move the ball through the stone ring up high.

After Chichen Itza, we had lunch at a beautiful former mansion in Valladolid, a quiet colonial town. Then we swam in another cenote, which was even more impressive than yesterday’s. It had a rope running through the middle just in case you got tired from swimming in the calcium-rich waters. On our way out, we looked at the fossils inlaid in the cenote walls -- proof that the entire Yucatan used to be underwater.