You are upended or lying down.

  • Your only movement option is to crawl, unless you stand up and thereby end the condition (see Being Prone).

  • You have disadvantage on Fighting tests.

  • Fighting test against you has advantage if the attacker is adjacent to you.

You can be prone even when climbing, swimming, or flying. In these situations, you can't crawl, and "stand up" means "right yourself."

At the GM's option, lying prone reduces the height of your space for the purpose of determining cover.