From the CDC:
Protect Yourself and Others from COVID-19
Staying physically active is one of the best ways to keep your mind and body healthy. In many areas, people can visit parks, trails, campgrounds, and open spaces as a way to relieve stress, get some fresh air, and stay active.
While these facilities and areas can offer health benefits, it is important that you follow the steps below to protect yourself and others from COVID-19.
Visit parks that are close to your home.
Check with the park or recreation area in advance to prepare safely and to find out if the bathroom facilities are open and what services are available.
Carefully consider use of playgrounds, and help children follow guidelines.
Play it safe around and in swimming pools, hot tubs, and water playgrounds by keeping space between yourself and others.
Visit parks if you are sick with, tested positive for COVID-19, or know you were recently exposed to COVID-19.
Visit crowded parks or campgrounds.