Hueco, a Spanish word for “cavity” and “hollow,” refers to spherical depressions eroded into either a vertical or horizontal rock surface. Climbers use the word hueco to describe a rounded pothole that can be used as a handhold and foothold. Huecos are generally large holes or cavities, while small ones are called pockets. A hueco on a horizontal rock surface is a natural basin that collects rain water, which is essential for life in desert areas.

Huecos are commonly found at Hueco Tanks State Historical Park in Texas.