Marinus is a lunar impact crater that is located near the southeastern limb of the Moon.

At this location it is viewed at an oblique angle from the Earth, limiting the amount of detail that can be observed.

It lies due north of the slightly larger and dark-floored crater Oken.

The interior surface is marked by a number of tiny craterlets and dimples, as is the rim and inner wall.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Marinus.