Grotta dello Smeraldo

Grotta Smeralda - Grotta Verde - Green Grotto

Useful Information

Location: Positano, south of Napoli (Naples). Amalfi Coast, 5 km west of Amalfi on the coast road Strada Statale 163. (40°36'53.43"N, 14°34'0.99"E)
Open: APR to SEP daily 9-17.
OCT to MAR daily 10-16.
Fee: Cave: Adults EUR 5.
Boat ride inside: Adults EUR 10.
Classification: SpeleologyKarst cave Speleologysea cave ExplainBlue Grotto
Light: electric/natural sun light.
Guided tours: D=30 min. V=100,000/a [2000]
Address: Grotta dello Smeraldo, Strada Statale 163, Conca dei Marini, 84010, Tel: +39-089-871107.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


1932 discovered by a fisherman named Luigi Buoncore.
1956 artificial entrance tunnel.


The Grotta Smeraldo or Grotta Smeralda (Emerald Cave) was named after the characteristic green light inside the cave. It is caused by natural sunlight from outside which enters the cave through an underground passage, which connects the salt water lake in the huge chamber with the sea outside. The water filters the sunlight and only green wave lengths reach the cave.

We cannot explain why the light is green while mostly the water becomes blue, for example in nearby Grotta Azzura (Blue Grotto) on Capri. We suppose it is the orientation of the cave, the cave is located at the southern coast of the peninsula called Costiera Amalfitana (Amalfi coast). The passage goes southwards to the sea, so the daylight shines directly into the opening. The blue grotto is located on the northern coast of Capri, oriented towards the north.

There is a small parking lot at the coast road, a wide staircase going down to the sea. There is also an elevator. After paying the fee, visitors enter the cave through an artificial tunnel at the other end of the small cove self guided. Inside there is a jetty with numerous wooden boats. The boat ride is the actual tour, so after a short look around you may enter the next boat and enjoy the calm gliding of the motorless boat.

The main thing is obviously the green light. It may be seen all day, if it is sunny, which is actually the case every day during summer. The effect is most intense around midday, but it works more or less during the whole open hours of the cave. The cave opens when the sunlight reaches the cliff around the cave entrance in the morning and closes when the entrance is not sunlit any more in the afternoon. So entrance hours roughly follow the local sunset and sundown times.

The cave consists only of a single huge chamber. The lake inside is 45 m by 32 m big and the chamber is 24 m high, above the sea level. There are some speleothems, as this is actually a karst cave. The cave was formed above the sea level, at a time when the sea was much deeper. Later the sea rose and flooded the entrance, or better the land went down, which is caused by the volcanic activities in the area. Some stalagmites on the floor were flooded.

Numerous reviews on the web dub this cave a ripoff. Actually it is not very expensive but the cave is very small and the whole visit takes only half an hour including stairs, cave, and boat ride. It is also essential to visit it at the right time. August is generally bad, because of the huge number of visitors, and we guess its annoying to wait a long time for a rather abbreviated tour. Go around 13:00 because the sunlight will be optimal and most people are having lunch at this time. The guides on the boat expect a tip, although the ride is included in the entrance fee. Many people feel pushed if the guides insist on the tip. However, the alternative way to reach the cave by boat seems to be the main problem. There are expensive boat trips to the cave entrance, offered by local boat owners, which are not connected with the cave and do not include the cave ticket. Visitors feel cheated if they have to pay a second time, and a third time for the boat inside. We do not know why the cave owners do not stop this, because they get a lot of bad reviews on the web.