Travelling on the arms, canals and lakes at the mouths of the Danube, tourists will undoubtedly wonder about their birth, about the genesis of the entire ecosystem of the delta. Indeed this is a real realm of passionate problems, wich required considerable efforts for the scientists. We contend this, because passionate scientific debates were held on the genesis of the delta, hypotheses were advanced, wich could be confirmed or invalidated by obvious testimonies alone. z4s22so

Geographic Location

The Danube Delta lies at the intersection of parallel 45o Eastern latitude and the longitude 29o East. The northernmost point of the Romanian delta is the locality „Chilia Veche” (latitude 45o 25` north) and the easternmost the town of „Sulina” (longitude 29o 42` east), also being the easternmost pint of Romania.
As a geographical unity, the Danube Delta has the following limits:
· To the north ? the Buceag Highland
· To the south-west ? the Tulcea Hills
· To the south-east ? the Black Sea

Relief

The Delta is a wide-stretched surface, we could even say an even area with an average altitude of only 0.31m. The low parts within the region are in the beds of the arms and lakes on the:
· Chilia arm (-36m)
· Sulina arm (-18m)
· Saint Gheorghe arm (-26m)
Then the lakes:
· Belciug (-12m)
· Rosu (-2,5m)
· Gorgova (-2,5m)
· Matita (-2m)
The highest altitudes are on the Chilia bank (6,5m), Letea bank (13m), as well as in the area of the Caraorman dunes, in the region of the Razelm lagoon complex, where the rocky islands of Bisericuta (4m) and Popina (49m) are located.

Hidrography

The hydrographic network of the delta is of a particular interest from the geographic, economic and tourist point of view. The hydrographic network supplies the lakes with water, with mineral and organic substances brought by the water, and secures travel to areas where it is not possible to go on foot. This network includes: the Danube arms, backwaters, and canals. As to the arms, they are four, of which only three have mouths at sea: Chilia, Sulina and Saint Gheorghe. The Tulcea arm is defined between the two “ceatals” (as the arms ramifications are called there) Chilia and Saint Gheorghe. The Tulcea arm and the Chilia arm initially were one of the two delta arms. Later on, the other two arms separated: Sulina and Saint Gheorghe. In order to avoid certain confusions, some researchers consider that only three arms should be taken into account: Chilia, Sulina and Saint Gheorghe. The Sulina arm has lost its initial natural character due to man’s
Intervention. At the beginning it was dredged just at its mouth soon after 1858, and later on all along its course, that is between 1880 and 1903, when due to the lay out, its length was shortened from 83.8 km to 62.6 km. By the improvements made by building groins, lighthouses, and laying slabs and beacons a.o., this water course has lost both its old aspect and the name of arm, being put down on maps and papers as a “canal”. The improvement and upkeep work at the Sulina canal was not confined to the mentioned period alone it was continued, since it is a waterway of international importance, being part of the Danube’s maritime sector with a total length of 170 km.
The hydrographic network is quite complex and the reader will be able to pursue it easily both on the map and on the sketches showing tourist routes.

Flora and fauna

The vegetation of the delta grows in various suroundings: flowing water (rivers) , standing water (lakes, swamps), land liable to overflooding, banks, dunes, beaches. It is estimated that the Danube Delta includes about 1,150 plant species.
Plancton -; floatin microscopic plants -; and zooplancton -; floatin microscopic animals -; are quite abundant both in flowing and standing waters. Plancton is used by fish for food. The speed of flowing water does not allow the growth of large plants. Various algae species populate this dynamic medium, their number reaching some millions in one cubic metre.