Objects such as empty beer bottles with the cap put back on can also explode when thrown into a fire. On another note, if rocks are to be intentionally used in a fire for a sauna, they need to be crystalline igneous rocks or metamorphic rocks derived from igneous rocks. These types of rocks are free of pores and cracks in which moisture can hide. Flash floods are common after heavy rains in the Ozarks. A dry creek can come up in minutes and become very dangerous.
Flash floods are also a hazard in underground caves.
Caves are created by flowing water and some act as natural storm sewers by collecting water from sinkholes and fractures in surface bedrock. Storms can also produce lightning, hail, and high winds. When in a storm, try to take cover and stay away from high points. These points are more likely to be struck by lightning and tend to be hit with more wind than other locations. When enjoying the outdoors, keep an eye on the weather.