The Danube Delta is the second largest river delta in Europe, after Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Romania (Tulcea County), while its northern part, on the left bank of the Chilia arm, is situated in Ukraine (Odessa Oblast).
The approximate surface area is 4,152 km² (1,603 sq mi), and of that, 3,446 km² (1,331 sq mi) are in Romania. With the lagoons of Razim-Sinoe (1,015 km² (392 sq mi) with 865 km² (334 sq mi) water surface), located south of the main delta, the total area of the Danube Delta reaches 5,165 km² (1,994 sq mi). The Razelm - Sinoe lagoon complex is geologically and ecologically related to the delta proper and their combined territory is part of the World Heritage Sites.