The map projection is called Simple Cylindrical, and the grid lines mark 10 degrees intervals of latitude and longitude. There are rugged mountains several km high, layered materials forming plateaus, and may irregular depressions called volcanic calderas. Dark, flow-like features may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters. The high resolution global view is centered on the side of Io that faces away from Jupiter.
North is to the top.
This image was taken at a range of 258,100 kilometers. It covers an area about 2080 kilometers wide and the smallest features that can be discerned are 2,6 km in size. The bright region beyond Io's limb is Jupiter's atmosphere. This one was taken at a range of 339,400 kilometers. It covers an area about 2600 kilometers wide and the smallest features that can be discerned are 3.5 km in size.