Geological Chronicle
Lacus Felicitatis, meaning Lake of Happiness, is a small patch of the lunar surface inundated by flows of lava, leaving a level area with a lower albedo than the surrounding ground. Situated in Terra Nivium, a region of continental ground north of Mare Vaporum, the feature reaches a maximum extent of 98.48 kilometers. Montes Haemus lies about 70 to 80 kilometers to the northeast along the southwestern edge of Mare Serenitatis, while the lake itself is bounded by an uneven border and surrounded by rugged surface.
The formation has a distinct bent outline, with one wing extending to the northwest and another to the east. Three tiny craters within the structure have received official names from the International Astronomical Union, including Ina, a semi-circular depression measuring about 30 meters deep.
Ina is notably difficult to image from Earth due to its shallow depth. In November 2006, researchers suggested that Ina resulted from a gas eruption in the last 10 million years.