Titan has three large seas. However, the seas of Titan are not filled with water, but are filled instead with swirling liquid hydrocarbons. All three of Titan's exotic seas are close to its north pole, and they are surrounded by many smaller hydrocarbon-filled lakes in the northern hemisphere.
For this reason, astronomers have for years considered the possibility that hydrocarbon lakes and seas might exist on the surface of this misty moisty moon. The data derived from Cassini/Huygens validated this prediction. During its long and productive mission, now over, Cassini revealed that almost 2% of Titan's entire bizarre surface is coated wth gasoline-like liquids.
Titan's atmosphere is approximately 95% nitrogen. However, in a way that dramatically differs from Earth's own mostly-nitrogen atmosphere, Titan's atmosphere has very little oxygen. Indeed, the remainder of Titan's atmosphere is almost entirely composed of methane--along with small qunatities of other gases, such as ethane. At the extremely cold temperatures that are found at Saturn's great distance from the heat of our Star, Titan's methane and ethane can accumulate on its icy surface to form pools of liquid.