The eastern basin of the Mediterranean is a remote area of the world ocean, the isolation of its various basins increased with distance from the Atlantic Ocean and with further constraints posed by the various straits. This chapter analyzes the deep‐water characteristics independent of the changes in the upper‐water column. It provides the data sources and methodology, followed by an analysis of the changes in basinwide properties linked with the interactions between individual basins of the eastern Mediterranean, and the intrabasin variability. The chapter compares the general deep‐water characteristics of the main subbasins of the eastern Mediterranean, namely, the Aegean and Adriatic shelf seas and the deep Levantine and Ionian basins, through a discussion of the water properties at the most relevant depth for each basin.