The Aper Tief is a stream in Lower Saxony, Germany.

It flows through the municipalities of Apen (district of Ammerland) and Detern in the collective municipality of Jümme (district of Leer).

It begins west of Apen at the confluence of the Große Süderbäke and the Große Norderbäke, runs roughly east–west and empties south of the municipality of Detern into the Jümme.

Including its source river Große Süderbäke, its total length is 31.4 km (19.5 mi).

Its tidal range is about three quarters of a metre.