Calanques Cassis France

A calanque is a narrow, steep-walled inlet that is developed in limestone, dolomite, or other carbonate strata and found along the Mediterranean coast. A calanque is a steep-sided valley formed within karstic regions either by fluvial erosion or the collapse of the roof of a cave that has been subsequently partially submerged by a rise in sea level.
Data from: en.wikipedia.org