Called Green Geocache to encourage green living! Bring a garbage bag with you for this one, and collect some garbage while you're at the park if you're able - be sure to comment that you cleared some garbage when you found it.
BYOP (bring your own pencil or pen)
You may need tweezers for this one, to get the log out.
Please don't untie the string, just unscrew the lid of the geocache.