Lake Covão dos Conchos, located on the highest mountain range in Portugal, Serra de Estrela, is home to a giant hole ... Oddity of nature? Not even! This hole is actually an artificial dam built in 1955. With a circumference of 48 metres and a height of 4.6 metres, the dam of Lake Covão dos Conchos was designed to collect the waters of the river Ribeira das naves to transport them to the Lagoa comprida lagoon. The waters stretch over a distance of 1519 metres. To admire this spectacular view, the Portuguese Daniel Alves recently gathered impressive aerial images using a drone.