The Adriatic Abyssal Plain, more commonly referred to as the Adriatic Basin, is an oceanic basin under the Adriatic Sea. The Adriatic Sea's average depth is, and its maximum depth is ; however, the North Adriatic basin rarely exceeds a depth of .
The North Adriatic basin, extending between Venice and Trieste towards a line connecting Ancona and Zadar, is only deep at its northwestern end; it gradually deepens towards the southeast. It is the largest Mediterranean shelf and is simultaneously a dilution basin and a site of bottom water formation. The Middle Adriatic basin is south of the Ancona–Zadar line, with the 270m (890feet) deep Middle Adriatic Pit (also called the Pomo Depression or the Jabuka Pit). The 170m (560feet) deep Palagruža Sill is south of the Middle Adriatic Pit, separating it from the 1200m (3,900feet) deep South Adriatic Pit and the Middle Adriatic basin from the South Adriatic Basin. Further on to the south, the sea floor rises to to form the Otranto Sill at the boundary to the Ionian Sea.
The South Adriatic Basin is similar in many respects to the Northern Ionian Sea, to which it is connected.