Blue Cave

Along the coastline between Kas and Kalkan, roughly 18 kilometres from Kas and about six from Kalkan, a narrow opening in the cliff leads into what locals call the Blue Cave, or Mavi Magara. It lies a few hundred metres short of Kaputas Beach, on a stretch of the Turkish Mediterranean where the mountains drop straight into deep water and the coast road is cut into rock high above the sea. The cave was first surveyed in 1972 by the Turkish geologist Dr. Temucin Aygen, whose work brought a place long familiar to local fishermen to much wider attention.

Where the Blue Comes From

Inside, the cave measures around 50 metres long, 40 metres wide and up to 15 metres high, with an entrance sitting barely a metre above sea level, low enough that visitors usually have to duck or swim in rather than walk. The colour is not pigment in the water or mineral in the rock but a straightforward optical effect. Sunlight entering at a low angle refracts as it crosses from air into water and bounces off the pale limestone seabed before reaching the eye. Blue is the part of the spectrum that travels furthest through seawater, so blue is what comes back, and the chamber fills with a glow that looks almost phosphorescent.

The effect is strongest close to the entrance and weakens the further in you go, which makes the timing of a visit matter more than most people expect. Morning light, with the sun still low over the sea and shining into the opening, gives the most vivid results; by mid-afternoon the angle has shifted and the interior is noticeably duller. Beyond the reach of daylight a torch is the only way to see the walls at all.

Chambers, Corals and What Lives Inside

The cave is not a single hollow. Turkey's culture ministry describes it as a large cave with several chambers and channels, divided into an outer and an inner gallery. The outer section is the part most boat passengers see: broad, well lit and shallow enough to swim across comfortably. The inner gallery is darker and tighter, reached through constricted passages, which puts it beyond casual swimmers and firmly in the territory of experienced snorkellers and divers working with a guide.

The rock surfaces are covered in soft corals, and in some seasons dense swarms of shrimp gather in the inner galleries. Mediterranean monk seals were recorded using the cave in the past, and the species still clings on along this coast: monitoring between 2019 and 2023 found seals using nine of the twelve caves watched continuously between Gokova and Kas, with nine to ten individual animals identified in the Kas area alone. Sightings are a matter of luck rather than something to expect, and the seals abandon caves that are disturbed, which is the main reason for the protection rules that apply here.

A Protected Coast

The cave lies inside the Kas-Kekova Special Environmental Protection Area, which covers about 258 square kilometres in total, some 92 of them marine. Surveys have recorded in the region of 1,000 marine species within its boundaries, including loggerhead and green turtles as well as the monk seal. Since 2019 a marine ranger system has operated in cooperation with local authorities to curb illegal fishing and pollution, with fish biomass, seawater temperature and seal presence all monitored. The water here is consistently clear and the seabed drops away steeply close inshore, which is why the Kas coast has become one of Turkey's better-regarded diving destinations.

Getting There and What Else Is on the Route

There is no land access. The entrance opens onto open water at the foot of a cliff, and the only ways in are by small boat or by swimming from one. Kaputas Beach just along the coast, by contrast, is reached down a staircase of roughly 190 steps from the D400 coastal road, where a canyon fed by underground spring water opens onto the sea and gives the bay in front of it that startling turquoise colour.

Kas itself, the base for most of these trips, is built over the Lycian town of Antiphellos, which began as the harbour of Phellos in the hills inland and eventually outgrew its parent to become an independent city in the Hellenistic period. Its small theatre, cut from local limestone for an audience of around 3,000 and unusually turned to face the water rather than the land, still stands on the slope above the western edge of town, and Lycian rock-cut tombs are scattered through the streets and the cliffs behind them.

Because it can only be reached from the water, the Blue Cave is typically visited as a stop along a boat itinerary rather than on its own, and it is one of the anchorages you'll visit on a private gulet charter from Kas that also takes in the Kekova coastline further east. Full-day boats leaving Kas harbour generally run six to seven hours and combine swimming stops with the sunken Lycian city off Kekova island, where an earthquake dropped walls, stairways and quays below the waterline, and the car-free village of Kalekoy, ancient Simena, still reachable only by boat. Shorter trips run from the fishing village of Ucagiz, the closest harbour to the ruins. The Greek island of Kastellorizo, called Meis in Turkish, lies only about 2 kilometres off this coast and is visible from much of it.