Europe, Italy, Campania, north-western coast of Capri island
Name in Italian:
The Blue Grotto in Capri became a sensation among the Romanticists of Europe in 1830ies - mostly thanks to the eerie blue glow of water inside the cave. And it truly is a romantic retreat entwined with legends and true stories of the past.
This by far is not the only blue grotto in the world - but certainly the most famous one.
Blue color has the shortest wavelength in the visible spectrum of light. As the sunlight enters the water, first are absorbed the longer waves - red color, then one after another - other colors. The deeper one goes, the less colors remain. Blue light is the last one: when it ends, there is only darkness.
Cave with two entrances
This is the effect with causes the eerie illumination in the famous Blue Grotto - sea cave in the north-western coast of Capri island. Cave has two entrances - a smaller one (1.5 m wide) at the waterline and at least ten times larger one - below the sea. A small 1 - 2 m thick barrier below the sea level divides both entrances.
Thus - a little sunlight enters through the upper hole - and this bright spot of light does not allow to see the large hole below it. A lot more light enters through the enormous underwater hole. Alas, other colors are absorbed in the water and only blue light reaches the interior of the cave. As a result whole 54 m long and up to 15 m deep cave is illuminated with a mysterious, phosphorescent blue light. Visitors to the cave are illuminated from below, and if one puts his hand in the water, the skin is glowing eerily.
One more interesting feature is sulphur springs at the bottom of cave - thanks to this the cave is very rich with marine life.
Imperial swimming pool
There was a time (27 - 37 AD) when the seat of Roman Empire was in Capri island - Emperor Tiberius decided that his life would be more safe on this secluded island. Several posh villas were built on the island and Tiberius enjoyed dissolute way of life here, mostly forgetting about the obligations of emperor.
Tiberius and his people knew about the existance of the Blue Grotto - and the cave was turned into imperial swimming pool. It was adorned with statues - most likely a group of Tritons blowing shell horns and led by Neptune. Emperor was bathing here among naked boys and girls - and, according to legends, he could access the cave directly from his villa through an underground passage. This passage has not been found (or at least - this is not announced) - may be it has collapsed since then.
Decline and rediscovery
When Roman Empire fell, splendid villas of Capri were destroyed in the Middle Age. It seems, also the statues in Blue Grotto were broken - none are in their places. Three statues - two Tritons and Neptune - were found below the water in 1964, bases of seven statues were found in 21st century. Local heritage organizations dream about the day when exact copies of the ancient statues will adorn the cave again.
Cave was known to local people and occasional guests to Capri. It was considered to be a Devil's den and locals did not enter the cave.
Blue Grotto became a true sensation in 1826, when a Polish - German poet August Kopisch together with his friend Ernest Fries visited the cave on directions of local fisherman Angelo Ferraro. Kopisch was greatly impressed by the otherworldly beauty of the cave and described it in his book "Entdeckung der blauen Grotte auf der Insel Capri", issued in 1838. Thus the cave became well known among the Romanticised young Europeans and has been a popular tourist destination since then.
Today the cave is visited by some 250,000 tourists every year. At high and/or stormy water it is not accessible but at better weather it is crowded. Tourists come by motorboats or descend steep ladder to enter smaller boats. The best time to visit the cave is at the midday, when the Sun shines in the cave. In cloudy weather there is no blue shine in the cave.
One boat comes out of the unsighty hole in the cliff - and another enters it. Tourists bend down to pass the cliffs - and for some minutes enter into this fantastic realm.
It happens, sometimes the cave is closed due to very unpleasant reason - water pollution. Well, such is the mass tourism. Nevertheless: Blue Grotto IS beautiful.
Every year there are reported exciting discoveries of new caves and discoveries of new qualities such as cave paintings in the ones known before. But there still is a feeling that our knowledge covers just a small part of all these monuments of nature.