Titan’s lakes are reminiscent of karstic landforms that we have on Earth, which form when dissolvable rock (like limestone) erodes as groundwater and rainfall move through it, resulting in sinkhole-like depressions.
Liquid hydrocarbons on Titan play a similar role to water on Earth: the hydrocarbons have caused erosion of dissolvable rock, resulting in a vast network of lakes and river-like formations that carry liquid across the moon’s surface. The large lakes stretch hundreds of miles across and several hundred feed deep.
via How Did Lakes Form on Titan’s Surface? | Discovery Blog | Discovery.