The island of Capri has long been a jewel in Italy’s crown, a place where nature, history, and culture converge in a breathtaking tableau. Yet, even among its many wonders, the Grotta Azzurra stands out as a one-of-a-kind beauty that captivated the imaginations of travelers, artists, and scientists alike. But what is it that makes the waters of this cave so ethereally blue?

The Grotta Azzurra’s iconic blue hue is a blend of natural phenomena and optical wonder. When sunlight filters into the cave, it must pass through an underwater opening that acts as a sort of natural lens, and this subaqueous passage allows only certain wavelengths of light to penetrate the cave’s interior, creating a unique interplay between light and water.