Day Five marks our final full day of diving and the anticipation is high as we head out to our last lead, driving through the scrub down endless stretches of dirt road, halting occasionally to hack at fallen trees blocking our way. Finally, we stop at a ramshackle pasture seemingly in the middle of nowhere. Behind a stone enclosure are a handful of sad, bony cows. In front of the enclosure is a treehole-type cenote with a series of metal pipes rising out of it and an electric pump alongside. The air is thick with wasps and the smell of slowly baking manure. We take a minute to let the scene sink in. Finally, someone breaks the silence: "God, we're really desperate, aren't we?"

As Memo heads down the rusty, half-broken ladder to take a first look, a beautiful electric-blue tôh, a bird that lives in cenotes, shoots out of the hole. A good sign. Memo comes back up. "There's a lot of water down there--let's go diving!"

Left, Diana gets ready for the descent. Right, puzzled cows look on as scuba equipment is dropped down the well. (Alisa French)

The ladder stops on a small, muddy mound surrounded by water on all sides. We're in a 30-foot-high cavern about the size of a tennis court. Memo heads underwater first and does a quick survey while the rest of our five-person team gears up. It can be phenomenally tricky to hoist on and buckle into a hundred pounds of scuba equipment while sitting on a muddy patch of rock, and then somehow slip into a shallow basin of water without disturbing the silt or any possible artifacts beneath you. Then, on top of that, to pull it all off in the near dark in a stuffy cavern.

Memo returns before we have all managed to get ourselves in the water. "I don't think there are any artifacts here," he sighs, bobbing on the surface. "I don't know, I just did a quick dive but I saw nothing, nothing." There's a collective groan. "Still, there's a nice cave back there, let's have a quick look, OK?" Memo turns on his small flashing strobe and drops it beneath him. "We're not entering the cave, but there are some points where you're swimming around very large rocks. If you get disoriented, just look for the strobe and you'll know which way is out."

We dive down to the mouth of the cave, at about 130 feet, and have some fun swimming between the enormous boulders and taking photos until the camera jams. Heading back, we half-heartedly spread out along the debris pile. Eighty feet, nothing. Sixty feet, nothing. Then at around 40 feet, a small but significant find: a fragment from a ceramic incense burner with two lozenges and "Maya blue" paint, very similar to Postclassic (A.D. 900-1500) incense burners from the nearby site of Mayapán. Everyone scrambles. On either side of the slope leading down to the cave are small niches, too narrow to fit a tank-wearing scuba diver through. We peer into the niches and find finger bones and pottery fragments. There's a little more pottery--small sherds scattered across the mound. Suddenly, Diana's hovering over the strobe light, motioning like crazy. Memo has inadvertently dropped the strobe not six inches from an exquisite ceramic animal head the size of a child's fist--perhaps a squirrel or a rabbit--sitting upright in a broken pot and surrounded by tiny polished agates. It's the top of another incense burner, and it seems that the lowly Cow Hole may have been a significant ceremonial site some time long ago.

Memo negotiates a tight squeeze in Cow Hole. (Melisa French)

Though we spend most of the day combing Cow Hole we certainly don't cover all of the site, and the incense burner top is our most significant find. When we finally climb out of the cenote, everyone hurries to break down their gear and get back on the road--it's time to go see the shaman.

Fortunately, we aren't too late this time, and Don Paco has us sit in chairs arranged in a wide circle in the main room of his traditional Maya house, empty save for a dresser, a hammock, a television, and a bicycle. He nods expressionlessly as Memo proudly fills him in on our latest discovery. Then the shaman speaks a bit about his own training, about how he learned at the hand of a man who practiced both black (bad) and white (good) magic when he was 18. But, Don Paco insists, he only practices white magic.

Memo asks him about the spirits that dwell in cenotes. This is of particular interest in his academic studies. "There are both good and bad spirits that live in cenotes," he says, "but as long as you enter a cenote with respect, and a good prayer in your heart, you will be protected from harm." In addition, he can invoke others to watch over a person before he or she enters a cenote or anywhere in the Underworld that spirits dwell.

Don Paco takes us into the back room, where there's an elaborate altar set up on a side table, including statues of saints, fresh flowers, and the Maya Cross, a crucifix that also represents the four cardinal points of the Maya universe. One by one, the shaman has us sit in a chair before the altar and hold a lit candle while he waves a bundle of herbs over our head and invokes a litany of Catholic saints and native gods in a mix of Spanish and Mayan.

Before we leave, Memo asks Don Paco if he can attend the next cha-chac ceremony. This evening's events have left the professor bursting with additional questions but once again it's much too late to start asking them. Don Paco readily agrees.

Do we leave that night with a feeling of spiritual invincibility, ready to take on any cenote we encounter? Hard to say. It's essentially the end of the expedition, and we only have a quick dive scheduled for tomorrow. But we do have a date with a crocodile.

Click here for more on modern Maya shamans.