Ladoga Lacus (Titan)

Lake in Russia.

Ladoga Lacus is one of a number of "methane lakes" found in Titan's north polar region. The lake, detected in 2004 by the Cassini space probe, is composed of liquid ethane and methane. (wikipedia entry)

A lacus is a "lake" or small, dark plain with discrete, sharp boundaries. On Titan they are named after lakes on Earth, preferably with a shape similar to the lacus or lacuna on Titan.