An ancient under sea valley carved in the ocean floor is known as a canyon, usually given the name of the contributory river on the land.
such as the Hudson Canyon, or the Clutha Canyon.
Flood Plains
A valley underwater is called a submarine canyon. These can form through a variety of geological processes, such as erosion by underwater currents or the collapse of underwater sediment. Submarine canyons can be important habitats for a diverse range of marine life.
A valley that is underwater.
A valley that is underwater.
An underwater bubble blower.
Areas of underwater ground are called seabeds or ocean floors.
The island of maui is covered with many valleys created from the underwater volcanoe when it erupted hundreds of years ago. It is called the valley island because if you were to fly over the island, the first feature you will notice are the multiple valley's covering the surface of the island. Compared to the other hawaiian islands(Kauai, Oahu, Lanai, molokai, Hawaii, etc.) Maui has the most valleys. So basically, Maui is valley island cause it is covered with valleys, though some are too small to be officially called a valley.
It is called the 'Tucker Valley'
shark valley is called shark valley because it is a valley that flows into shark lake
Underwater sound detecting systems are called hydrophones. These devices are used to listen to and record sounds underwater, such as those produced by marine animals or underwater activities.
An underwater bomb is called a 'depth charge.
Being completely underwater is referred to as being submerged.