New Horizons mission scientists believe they were formed through a combination of ice fracturing and evaporation.
The lack impact craters also suggests the patterns formed relatively recently. For an idea of scle, the pits are typically a few hundred metres across and tens of metres deep.
The image was captured on 14 July with the telescopic camera on the New Horizons spacecraft as it sped past Pluto 15,400 kilometres above Pluto’s surface.
The small box on the global view shows the section of the region imaged in the southeast corner of the giant ice sheet informally named Sputnik Planum. The magnified view is 80 x 80 kilometres.
The large ring-like structure near the bottom right of the magnified view, and the smaller one near the bottom left, may be remnant craters.
The upper-left quadrant of the image shows the border between the relatively smooth Sputnik Planum ice sheet and the pitted area, with a series of hills forming slightly inside this unusual “shoreline”.
Meanwhile, below, NASA has released an enhanced colour mosaic of the image of Pluto’s giant ice mountains that was was released this week.
NASA has provisionally named the region the al-Idrisi mountains, which consists of massive blocks of ice, some standing up to 2.4 kilometres high and showing signs of being violently rammed up against each other.