YouTube filmmaker Cory "Mr. Safety" Williams, aka DudeLikeHELLA, discovers the bizarre sounds skipping rocks on frozen lakes can create (the rock skipping starts at 3:41)
According to Cottage Life, "Ice vibrates up and down, similar to a drumhead or cymbal vibrating after being struck. Different ice produces different sounds: A high-pitched noise when your rock hits the lake likely means you have "clear" ice. This is the glassy, see-through ice that's formed under cold, still, non-snowy conditions. "Snow" ice -- the opaque ice that forms after snow falls on the surface of the lake, becomes saturated with water and then freezes -- produces a lower-frequency sound, because fine grains in the ice absorb some of the noise."
Williams moved to Alaska last August and, along with his girlfriend, has been documenting his adventures. Watch more of DudeLikeHELLAs escapades in Alaska on his YouTube channel. He previously had Internet acclaim through his other YouTube channel SMPFilms, where you can see skits and stunts, including shock collars and mean cats.