One of my favorite excursions of this trip was a visit to Hierve el Aqua (the water boils).
First, Frida and I walked to the collectivo stand in Oaxaca city and after asking for directions 5 times, we finally managed to find the collectives heading to Mitla. We jumped into a public taxi and for 35 pesos each, we rode 50 minutes outside of Oaxaca city to the small town of Mitla.
Once in Mitla, we immediately found the "tours" that take you up to Hierve el Aqua. It's really just a few beat up covered trucks that wait around for budget travelers like ourselves. They hold 8-11 people, and if full, you only have to pay 35 pesos roundtrip. We waited for about 45 minutes, and then got too impatient and so bargained with the driver, settling on a 80 peso roundtrip journey.
Off thru the desert we went - up a winding mountain road, hurtling past donkeys and enormous cacti and kicking up a crazy dust storm.
The 45 minute ride ended at a small tourist alcove complete with bathrooms, cafes, a few shops, and a few cabanas. We bought water, mezcal, and chips and then walked a short ten minutes to the first cliff. Hierve el Aqua consists of two rock shelves or cliffs that rise 50-90 meters above the valley. They are created by natural fresh water springs whose water is over-saturated with calcium carbonate and other minerals. As the water meanders over the cliffs, the excess minerals are deposited creating what looks like white petrified waterfalls .
The first cliff, known as Cascada Chica, has 4 springs, 2 artificial pools, and several small natural pools. Here, visitors can "swim" in the water that is said to have healing qualities while looking out over an incredible mountain vista. Due to the various minerals, the water can appear vivid blue or green and is a nice cool temperature.