This can be seen only in a few places.
On most maps is not specified the boundaries of seas, rivers and oceans, so it seems that they just fade into each other and into the oceans. But in fact the boundaries of the seas are not only on the seabed. Different density, salinity and temperature lead to the fact that at the junction of the seas is like bumping into each other two walls. In a few places on Earth this is even visually noticeable.
Tuzla spit. Left the sea of Azov, the Black sea on the right
To see this phenomenon with your own eyes, go to the Danish town Skagen. Then you will see a place where the North sea with the Baltic. On the border of the watershed is often possible to observe even small waves with whitecaps: it’s bumping into other waves of the two seas.
The confluence of the Rhone and Arve rivers in Geneva, Switzerland. Left the river Rhone which flows from lake Leman, on the right the Arve receives water from the glaciers of Chamonix. Arvert has a deeper silt layer at the bottom of this, its waters so strongly contrasted with the Rhone.
The confluence of Thompson and Fraser, British Columbia, Canada. The Fraser river fed by the waters of the mountains and therefore has more turbid water than the current across the plains of the Thompson river.
The confluence of the Green and Colorado National Park, Utah, USA Green River is formed in the Rocky mountains National Park “Les Sublette” Wyoming. It winds its way South into Utah, turning East into Colorado and finally back South into Utah, where it ends its way to the confluence with the Colorado river. Water color vary because of differences washed them rocks.
The confluence of the Green and Colorado National Park, Utah, USA Green River is formed in the Rocky mountains National Park “Les Sublette” Wyoming. It winds its way South into Utah, turning East into Colorado and finally back South into Utah, where it ends its way to the confluence with the Colorado river. Water color vary because of differences washed them rocks.
The confluence of the Bhagirathi and Alaknanda , India near the town of Devprayag two rivers feeding their water glaciers in the Himalayas. In the future, these two sacred rivers form the Ganges river.
The confluence of the Bhagirathi and Alaknanda , India
The confluence of the Rio Negro and Rio Solimoes, Manaus, Brazil This phenomenon is due to differences in temperature, speed and water density of the two rivers. Rio Negro on the right carries the sand-colored water mixes with the almost black waters of the Rio Solimoes
The confluence of the Rio Negro and Rio Solimoes, Manaus, Brazil
The confluence Jialing and Yangtzе Chongqing, China Jialing River length of 119 kilometers on the right falls into the river Yangtzе in Chongqing. Clean water strongly contrasts with the brown – yellow waters Yangtzе
The confluence of the rivers Mosel and Rhine in Koblenz, Germany
The confluence of the Drava and Danube Osijek, Croatia
