Picture of Pitted Keratolysis
Pitted keratolysis is a skin disorder that's caused by bacteria. It creates crater-like pits or small holes on the top layer of your skin and usually affects the soles of your feet, but can also develop on the palms of your hands. It's more common in people who often go barefoot and live in tropical areas or wear occlusive shoes, which are shoes that create warm and moist environments for bacteria to thrive as they surround your feet.
Text Source: WebMD