drowned valley; ria
Geological term for a coastal valley flooded by rising sea levels, forming a ria.
A drowned valley is a landform created by rising sea levels.
リアス式海岸には多くの溺れ谷が見られる。
Many drowned valleys can be seen on ria coastlines.
Compound of 溺れ (drowning) and 谷 (valley), directly describing a valley submerged by the sea.