Saint Marys Ballfield is one of the California parks in thicket's catalog. thicket is a field guide to the parks near you: it maps the ones you have never noticed, gives you a reason to actually go, and keeps a record of where you have been.
Where it is
Saint Marys Ballfield is in Contra Costa County, California. Its approximate coordinates are 37.87618, -122.10090.
Check in at Saint Marys Ballfield
thicket verifies you are actually here by GPS when you check in, so a visit means you went. Checking in builds a streak, earns achievements, and fills in your map of the places you have been.