noun
rias coastline; deeply indented coastline
A geographical term for a coastline with many inlets formed by the submergence of river valleys; often used in descriptions of coastal topography.
三陸地方はリアス海岸で知られている。
The Sanriku region is known for its rias coastline.
リアス
Rias coastlines, due to their complex topography, tend to suffer greater damage from tsunamis.