It appears as a kind of magical portal to a watery underworld.
This mesmerising whirlpool, known as Covao do Conchos, has churned away for 60 years in the middle of an otherwise tranquil body of water among the mountains of the Serra de Estrela in Portugal.
And this breathtaking drone footage has provided a closer look at the phenomenon, which is so surreal it’s been compared to a mythical sea monster in Homer’s The Odyssey.But what is it?
Anyone searching for a mystical gateway to another dimension might be disappointed from here.
The Covao de Conchos is entirely human-made. It’s actually part of a hydro-electric dam system that was built in 1955.
Named Covão do Conchos, the strange, almost otherworldly cascading cavity is an example of a ‘bell-mouth spillway’.
A spillway is a structure within a dam used to divert water to a downstream area. In this case, a 1.5km tunnel, so that the water doesn’t spill over the top of the dam and damage it.
The water usually only flows into the spillway during flood periods, meaning this spectacle can only be seen for a short time every year.
So if you’re ever in Portugal and it’s raining, don’t despair – make a point of going to see this swirly sight.
The dam was built sometime in 1955 and it has a spillway tunnel which measures to around 4,984 ft. in length. The water dries up in the summer, but it’s overflowing in the winter, which leads to the formation of this hellish looking natural beauty.
There is no official record of this anywhere, and three Portuguese travelers chanced upon it while hiking
Back in 2014, they were hiking among the terrains of the Serra da Estrela, along the banks of the lake, when they stumbled upon this spill hole. They had camera gear and shooting equipment, and hence they decided to make a video of its beauty and put it up for the world to see.