Covão dos Conchos is an artificial lake in the Serra da Estrela mountains in Portugal that is famous for its Bell-mouth spillway.

[1] The spillway was built in 1955 with the aim of diverting water from Ribeira das Naves to Lagoa Comprida.

It is a part of a hydro-electric dam system of Serra da Estrela.

[2] The conical spillway was little-known until photos of the hole went viral in 2016.

[3][4][5][6] Over the last 60 years moss and foliage has grown onto the mouth of the funnel, creating an eye-catching sight.