The geographic coordinates

The Geographic Coordinates of the Danube Delta are between 44⁰47'25" and 45⁰37'30" North and between 28⁰44'25" and 29⁰46'00" East. The parallel of 45⁰ passes through the Delta, that gives it climatic features associated to a territory of great diversity (mainly amphibian), influenced by the Black Sea. The Danube Delta's surface (it is the second in Europe after the Volga Delta) is of 4 170 km² of which 3 445 km² (82%) lyies on the Romanian territory, and the rest of 18% is in Ukraine.

The Geographic Outline keeps the Delta's characteristics, the Danube Delta being a plain region (an alluvionary plain in the process of forming) slightly inclined from east to west 0,006% between Tulcea and Sulina, there is a distance of 60 km, therefore we have a difference of level of 3,60 m compared to the Black Sea level, 20,5% of the Delta's territory is below this level and 79,5% is above it. The greatest area is represented by the surfaces between 0 and 1m (54,5%) followed by the ones between 1 and 2 m (18%). The highest areas are on the sand banks of sea origin (Letea 12,4 m and Caraorman 8 m) and the deepest areas are encountered in the Danube's branches (-39 m on Chilia, -34 m Tulcea, -26 m Sf. Gheorghe and -18 m Sulina). Among the Danube Delta's lakes, the deepest ones are about 3 m deep except the meander lake Belciug, 7 m deep. The average altitude of the delta is of +0,72 m.

The Delta's climate is continental temperate with sea influences, due to the geographic position and to the presence of the Black Sea. The continental feature of the climate is prevailing even though it is encountered next to the sea, and inside there are great surfaces of water. During autumn and spring there are strong storms because of the north-east winds. The average annual temperature is of 11⁰C (-1⁰C in January, 22⁰C in July), there are the values of the main climatic features as compared to Romania's territory:

The biggest period of sunshining (2500 hours/year - Sf. Gheorghe);
The greatest solar radiation 135 kcal 15cm/year;
The sunniest days 150-160 days/year;
The most reduced nebulousness;
The highest quantity of rain water in 24 h (690 mm on Letea sand bank in 1924);
The highest air humidity 180%);
The average annual value of evapo-transpiration (Tulcea 1990);

Delta's Ecosystems
The development of a diversified fauna and formation of the sand banks, lakes, brooks and swamps, led to the formation of unique ecosystem. Out of all 30 ecosystems, the most important are:

The ecosystem of flowing water: the Danube's branches, the channel and the brooks which cover over 2.5% of the delta's surface. The Danube now has 3 branches through which it flows to the sea: Chilia, Sulina, Sf. Gheorghe. The most important channels are: Litcov, Crisan, Caraorman, Pardina, Vatafu, Mila 35, and the most well-known brooks are: Perivolovca, Sontea, Lopatna, etc.
The ecosystem of still water: lakes, floods patches, channels and muddy brooks which represent 10% of the Delta's surface. The largest lakes are Dranov (21,5 Km²), Rosu (14,4 Km²), Gorgova (13.7 Km²), Lumina (13.6 Km²), Isac (11 Km²). There are 50 lakes that surpass 100 ha, and about 670 natural lakes with a surface largest than 1 ha. The largest lagoonal complex in Europe is Razime-Sinoe (731 Km²).
The ecosystem of swampy and flooded surfaces (of reed and reed islets), situated between -0.5 and 1m, take 67% of the Delta's surface.Details
The ecosystem of sand banks: sand banks of marine origin: Caraorman, Letea, Raducului, Saraturile (they have a transversal position on the Danube's branches, 270 Km² 8%) and sand banks of fluvial origin (represent the banks of the Danube and of the main brooks 200 Km², 6%).
Planed enclosures for agriculture, forest plantations and nursery ponds, which represented in 1991, 30% of the Delta's surface. These enclosures have totally changed the deltaic landscape and some of theme are planned on being reintegrated in the natural hydrographic system, because of their economical inefficiency. As a consequence of this, we are facing the regression of all fish species in the Delta.