The outer wall of Petavius is unusually wide in proportion to the diameter, and displays a double-rim along the south and west sides. The height of the rim varies by as much as 50% from the lowest point, and a number of ridges radiate outward from the rim. The convex crater floor has been resurfaced by lava flow, and displays a rille system named the Rimae Petavius. The large central mountains are a prominent formation with multiple peaks, climbing 1.7 kilometers above the floor. A deep fracture runs from the peaks toward the southwest rim of the crater.
Rev. T. W. Webb described Petavius as,
The most favorable time for viewing this feature through a telescope is when the Moon is only three days old. By the fourth day the crater is nearly devoid of shadow.
70cm radar images of this crater and its surroundings show that the region of the surface beyond the wide outer rampart of Petavius has a dark halo, characteristic of a smooth surface free of boulders. It is thought that this may have been created by radial outbursts during the original impact that swept the area "clean".
Petavius B to the north-northwest of Petavius has a small ray system that lies across the surface of Mare Fecunditatis.
|A||26.0° S||61.6° E||5 km|
|B||19.9° S||57.1° E||33 km|
|C||27.7° S||60.1° E||11 km|
|D||24.0° S||64.4° E||17 km|