Oken is a lunar

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 near the southeastern limb of the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. It is normally visible from the Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

, but is foreshortened and within the region of the surface that is subject to libration

Libration

In astronomy, libration is an oscillating motion of orbiting bodies relative to each other, notably including the motion of the Moon relative to Earth, or of Trojan asteroids relative to planets.-Lunar libration:...

. To the south and east of this feature is the broad, uneven Mare Australe

Mare Australe

Mare Australe is a lunar mare located in the southeastern hemisphere of the Moon. It is 603 kilometers in diameter, overlapping the near and far sides of the Moon. Smooth, dark volcanic basalt lines the bottom of the mare...

, which extends to the far side of the Moon.

The interior of this crater has become flooded by basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

ic lava

Lava

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

, producing a nearly level, featureless surface with a low albedo

Albedo

Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

. A number of tiny craterlets mark this surface, particularly in the northwest. The surrounding mountain ring has been eroded by impacts, and is somewhat distorted from a true circular shape. There is a wide bulge in the rim toward the southeast, where the surface is lower and more rugged. Slight bulges also exist to the southwest and northwest. The rim is marked by a number of tiny impacts along the edge, particularly to the southwest.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Oken.

Oken	Latitude	Longitude	Diameter
A	43.2° S	71.3° E	36 km
E	46.1° S	78.9° E	12 km
F	44.4° S	71.5° E	21 km
L	43.1° S	78.2° E	10 km
M	41.8° S	75.4° E	7 km
N	42.4° S	74.5° E	40 km