Adriatic Sea stretches from the northwest to the southeast between the Apennine and Balkan peninsulas for 783 km, its average width being 170 km. Its average depth is 252 meters: northwestern part is shallow, maximum 23 meters in the Bay of Trieste and much deeper in the south 1200 m in the South Adriatic basin. Major rivers joining the Adriatic are the Reno, Po, Adige, Brenta, Piave, Soča, Neretva. The Adriatic Sea is situated largely between the eastern coast of Italy and Croatia.
The west shore is generally low, merging, in the northwest, into the marshes and lagoons on either hand of the protruding delta of the river Po, the sediment of which has pushed forward the coastline for several miles within historic times—Adria is now some distance from the shore.
