its a large crack in the ground, usually in a "V" shape, where the tectonic plate have seperated, leaving a large gap in the ground
The Marianas Trench, and many other deep undersea valleys, can be found on the ocean floor.
Undersea volcanoes that erupt.
The Trieste was that famous submarine. It is actually considered a bathyscaphe, but the term submarine could be applied. It dove to the deepest undersea point in the world, the Challenger Deep in the Mariana Trench, where the water depth is nearly 36,000 feet. A link is provided to the Wikipedia article on this revolutionary undersea vehicle.
Undersea Fleet was created in 1956.
Undersea Quest was created in 1954.
Undersea Trilogy was created in 1992.
Undersea City was created in 1958.
It is known as a trench, which is the lower part of the ocean. The deepest trench is the Marina Trench.
The duration of Undersea Kingdom is 3.77 hours.
Undersea Trilogy has 501 pages.
Jules' Undersea Lodge was created in 1986.
Some islands may be built by undersea volcanoes.