THE BLUE CAVE, a brilliantly blue sea cave on the Greek island of Kastellorizo (or Kazzie for short), is an experience you’re not likely to forget. Why is it so blue? The light from the sun is refracted through the ocean which results in a clear turquoise water that looks like it’s being lit from below.

Nearly invisible from the outside, the cave, created through millennia of erosion, opens up to beautiful arches and textures. Not for the claustrophobic, the cave’s entrance is only a narrow slit—about a meter high—so in order to enter this azure temple, you’re going to need a really small boat (if the tide is right and the sea is calm) or a pair of swim fins.

Kastellorizo is one of the smallest islands in Greece, but it’s charming and definitely worth a visit—if only to put you in range of this natural jewel.

How to get there

The Blue Cave is located on the southeast coast of the island, accessible only by boat. Go to Megisti harbor and charter a ride with one of the many operators there. It’s a 40-minute boat ride and will cost around 20 euro per person.

What to consider

  • The best time of day to go is early morning, when the sun is still low.
  • At about 50 meters long, 30 meters wide and 25 meters high, the Blue Cave is bigger than the world-famous Grotta Azzurra in Capri, Italy.
  • The local name for the Blue Cave is Phokiali, which is Greek for seals’ refuge.
  • Sea lions will often swim in for a visit.
  • The cave is only accessible by boat when the seas are calm.