Basically a hole in the side of the cliff that is the Isle of Capri. The big boat arrived with small rowboats in tow. The group got into the rowboats, 4 people each. We each rowed into the hole in the cliff, ducking all the way flat as we went in. On the inside, it was a totally dark cave, except for the beautiful glow of the water. The sunlight comes in under the cave walls and illuminates the crystal azure waters of the Mediterranean. The guides' stories were that the ancient Romans swam "au naturel" in here. No doubt an inspiration for Hugh Hefner centuries later, with intentions of lesser nobility.