A Ria is a coastal landform characterized by a long, narrow inlet with a depth that increases from the coast seaward. It is essentially a drowned river valley.
Formation: Rias form when a rise in sea level causes the sea to flood existing river valleys on the land. The higher land surrounding the valley becomes submerged, leaving the valley mouth open to the sea.
Classification: This flooding process means that a Ria is a prime example of a Submerged upland shore. The 'upland' refers to the original river valley and surrounding higher ground, which is now partially underwater ('submerged').
Therefore, Ria is a classic example of a submerged upland shore.