Titan has clouds, rain, rivers, lakes and seas of liquid hydrocarbons like methane and ethane. The largest seas are hundreds of feet deep and hundreds of miles wide. Beneath Titan's thick crust of water ice is more liquid—an ocean primarily of water rather than methane. He is the largest Moon of Saturn and is very similar to the Earth. But it does look strikingly Earthlike in one respect—lakes with crinkled shorelines speckle its surface. Those lakes are filled with methane and ethane.