Its the biggest moon in the solar system, larger than mars, has a decent atmosphere and lakes on its surface.
Only challenge is they are not water lakes but ethane and methane lakes, although, as our sun enters old age and expand as a red giant it will warm up things on Titan enough for there to be liquid water on its surface for a couple of hundred million years.
By NASA - http://photojournal.jpl.nasa.gov/catalog/PIA14602, Public Domain, Link
