You can only visit the reserve accompanied by a licensed guide. Ours was Juan Diego.

You’re looking at a pool of salt water. This is fossil salt.The miners use the same process that’s been used for over 1,000 years.

This water is so salty that nothing lives in it for very long.

Strangely, there are a few fish. They live just long enough to reproduce.

The Tehuacán-Cuicatlán Biosphere is a UNESCO forest of 85 species of cactus.

To own land here, you have to be a resident of the region. They don’t want investors. There’s salt mining happening here, but it’s all sold locally, and at cost.

Our guide Juan Diego lead us up to the top. The path to the top was rocky and narrow. It was full of cactus, from tiny to huge.

One slip and you could find yourself full of cactus needles.

My dress would have been appropriate, historically speaking. Helia wore dresses and heels when she went into the field to study cactus.

Here’s Helia in a Wikimedia Creative Commons photo.

She studied the cactus here for her graduate thesis. Today, the botanical gardens are named after her. She was a cactologist.

The trip was starting to get interesting.

I found chunks of quartz and onyx, scattered everywhere. I love stones!

The local shops are full of artisan pieces made from onyx. I recommend a lot of time at the local shops. I’ll explain why else below.

65 million of years ago, a shallow ocean spanned from the Gulf of Mexico to the Pacific Ocean.

In this photo, Mary Carmen is showing me a fossil of a seahorse. She said there are even dinosaur fossils.

We found dry animal excrement along the trail. Juan Diego could tell it came from a coyote.

The right tour guide can make all the difference, and this tour was more interesting with every careful step. Sometimes, we’re forced to stretch ourselves.

Here I am with 10-year-old Valeria.

Valeria maneuvered the trail like a little butterfly, with no trouble at all. Meanwhile, her family was always catching up to us.

Valeria didn’t want to miss Diego’s explanations. She listened to every word he said.

Meet Diego and Mary Carmen.

Juan Diego survived three treks through the desert, illegally crossing from Mexico to the United States. He knows his stuff.

At one point, I notice I had a lot of small cactus needles in my pants. I’m not sure how. Diego picked them out with his bare hands!

Behind me, you see a dead maguey plant. Its flowers sprout just before it dies.

Mary Carmen brings the flowers home. They last for years.

Along the path, Diego showed us herbal plants that people use locally. We chewed on one leaf to measure our glucose level. If the leaf tasted bitter, our levels were fine.

The locals prepare different leaves in tea. That’s why you really need time for the local shops.

Valeria is from the local town of Tehuacán, but all this was new for her.

I told her to pursue this interest and maybe, some day, she’ll work for National Geographic.

She already had Helia as a role model. Helia became interested in plants as a child, too.

I want to show you a species of cactus called the Mexican fencepost cactus.

I took this photo at the Diego & Frida Home Studio in Mexico City.

You can see they used these cactus as a fence for their property.

They grow just millimeters each year, and they can be thousands of years old. The biosphere is full of these.