Watch Liev Schreiber Explain How Geocaching in Central Park Works

Actor Liev Schreiber spent his Father’s Day running around New York City with his sons looking for buried treasure.

Schreiber appeared on Jimmy Kimmel Live! on Monday and explained geocaching—an outdoor game where items are hidden around the world and then located using GPS.

“There’s this community of people who hide things and then they give you the coordinates and you find them,” Schreiber said. “You can take something or leave something—and we didn’t know you were supposed to leave something.”

The actor says he took his sons to get some magnets that read “New York” so that other geocachers would “know where we were from.”

Watch the full clip below.