Aquismón

The road from Ciudad Valles climbs into Huasteca hill country in the dark, which is when I arrived. My driver — a man named Guadalupe who hadn’t asked my name — navigated the curves without hesitation while I watched the headlights cut through fog and ceiba trees. Aquismón announced itself with a church, a square, a few lit fondas still open past ten. I had a room above a hardware store and an alarm set for four-thirty. That was the whole plan. In the morning I would understand why.

What Comes Up From Below

You walk the path to the rim in the dark with a headlamp and find a dozen other people already waiting at the edge. The Sótano de las Golondrinas is 370 meters deep and 60 meters wide at the top, so looking down is looking into pure black — the kind that has no bottom visible, no light, nothing. Then you hear it: a sound like wind in a stadium, except it is coming from below and it is getting louder. The column of birds rises before you can see individual birds. It comes up as a mass, a dark smoke, corkscrewing tight against the shaft walls and then widening as it clears the rim and breaks into the open sky. White-collared swifts mostly, though parakeets join them and later in the season so do parrots. The whole event takes twenty minutes. For twenty minutes, this is what the world is doing. I have stood at the rim of the Grand Canyon and felt something large but distant. This was neither large nor distant. This was happening directly beneath my feet.

The Huasteca Table

Aquismón is a Teenek town — the Huastec people have lived in this river country for centuries, and their language and market culture are still very present. The Saturday tianguis fills the zócalo with vendors selling tamarind, chaya, and zacahuil, the enormous tamale of the Huasteca: a masa log wrapped in banana leaf and cooked overnight in an earthen pit. I ate two portions at a folding table beside the church, served by a woman who corrected my pronunciation of her town’s name three times with patient amusement. It is Ah-kees-MOHN, not Ah-KEES-mohn, and apparently this matters. The Río Tampaón below town feeds into the Tamul waterfall an hour south — one of the tallest in Mexico, reached by lancha upriver through jungle — but I didn’t go that day. I stayed in town, drank tejocote agua fresca from a plastic bag with a straw, and walked back to the rim in the late afternoon to watch the birds drop back into the dark at dusk, which is the reverse spectacle and almost as strange.

On Timing

The morning flight happens year-round, but between November and March the white-collared swifts are most numerous and the column is at its fullest. Arrive the day before and sleep in town; driving from Ciudad Valles before dawn means a 4:30 alarm and a 45-minute road with no shoulders and no gas stations. The walk to the rim is fifteen minutes on a signed path from the parking area. Bring something warm — the jungle at 5 a.m. is colder than you expect when you’re standing still at the edge of a very large hole for twenty minutes. There is no café at the sótano. There is sometimes a man who sells coffee from a thermos. I gave him sixty pesos and considered it among the better investments I have made in this country.

Getting There

Aquismón is 60 kilometers from Ciudad Valles on Federal Highway 120 — about 45 minutes by car. Colectivos run between the two towns throughout the day, but for the dawn flight you will need your own vehicle or a taxi arranged the night before in Ciudad Valles. The town has basic but functional hospedaje. From San Luis Potosí city, plan on four hours by car through mountain roads.