Nestled into the eastern face of the Tinajas Atlas Mountains are a series of natural pools known as the Tinajas Atlas Tanks. For centuries, these were the only reliable water source in the area, and as such, have played an important role in its history. With time, visitors can climb into the mountains to seek out a series of gradually higher tanks—just don't rely on them for drinking water. When we arrived the water was stagnant and emerald green.