Hikes/views with an echo-echo-echo…?

Hello! My wife and I are watching my nephew from now through Sunday, with the nice weather we want to take him out and out a few times. He’s REALLY into the idea of shouting during a hike and getting a big echo back, something he keeps talking about from a TV show he saw I guess. Where can I take him where we can do a little hollering and hear our voices come back at us? He’s 7 so it needs to be reasonable to walk to, no 5 mile hike viewpoint if possible!