Key takeaways
- The cliffs on the south and west of Comino are cut through with openings, arches and hollows along most of their length.
- Several are large enough to take a small boat inside. No scheduled vessel will attempt it, which is why most visitors never see them.
- Sunlight enters, hits a pale bottom and comes back up, so the inside of a cave glows blue from below rather than from the entrance.
- Even a light swell moves water in and out of an opening. The skipper judges each one on the day.
Why an island this small has so many caves
Comino is made of limestone, and limestone is soluble, soft and jointed. The Mediterranean has been working on it for a very long time, exploiting every crack and weakness in the rock, dissolving from within and hammering from without.
The result is a coastline that is hollow in places along most of its length. There are openings at the waterline, arches where a cave has been eaten through from both sides, collapsed roofs that have left holes in the clifftop, and stacks left standing where an arch finally fell.
You can see the whole sequence on one short boat trip, which is unusual. Most coastlines show you a single stage of it and leave you to imagine the rest; Comino has caves, arches, collapsed roofs and free-standing stacks within a few hundred metres of one another.
What it is like inside
Cooler, quieter and blue. The temperature drops noticeably the moment a boat noses under the rock, the engine noise changes character, and everyone stops talking, which happens reliably enough to be funny.
The colour is the thing people describe afterwards. Light comes in through the entrance, passes down through clear water onto a pale bottom, and reflects back up into the chamber, so the cave is lit from below rather than from the doorway. On a bright day the whole interior glows.
Some of the openings connect: a boat goes in one way and out another, or a cave has a second hole in its roof that drops a shaft of sunlight onto the water inside.
A cave mouth in the Comino cliffs, lit from below by the water
Which ones a boat can enter
That depends on the boat and on the day. A small private craft with a skipper who knows the coast can enter several of the larger openings when the sea is calm. A larger vessel cannot enter any of them, and would not try.
This is the single clearest reason travellers give for having chosen a private charter here. The phrase recurs almost word for word in their accounts: they saw caves they would never have found, and could not have gone into, any other way.
The skipper decides on the day, and that judgement is worth trusting. An opening that looks perfectly calm from thirty metres away can be surging at the entrance, and a boat in a confined space with moving water is not somewhere to find out.
Where they are
Mostly on the south and west sides of Comino, away from the Blue Lagoon and away from the ferry routes. That geography is why they stay quiet: nothing scheduled has any reason to go round there, so the only boats in the area are the ones that chose to be.
There are caves and arches around the Crystal Lagoon on the eastern side too, including one large enough to take a boat, which is part of what makes that lagoon worth the short run round from the famous one.
The distances are tiny. Comino is small enough that a boat can be at the caves within minutes of leaving the lagoon, which is what makes it possible to escape the crowd at midday and come back later.
Swimming at the mouths
Snorkelling at a cave entrance is the best water on the trip. It is deeper than the lagoon, the light is dramatic, and the rock walls hold far more life than open sand does.
It also asks more of a swimmer, and it asks for sense. Stay where the skipper indicates, keep clear of the rock rather than holding onto it, and remember that a swell that is unnoticeable in open water becomes very noticeable in a narrow space.
Photographing them
Hard, and worth trying. The contrast between a bright entrance and a dark interior is beyond what most cameras record in one frame, so something is going to be blown out or blocked up. Expose for the water rather than the rock and the blue will survive.
The best frames are usually taken from inside looking out, with the opening as a bright shape and the interior as silhouette, or from just outside with the boat entering. A phone handles this better than people expect, largely because its processing is designed for exactly this kind of contrast.
When to see them
Middle of the day for the light, which is the opposite of the advice for the lagoon. The colour inside a sea cave depends on sunlight reaching the water and coming back up, and that needs the sun high.
Which produces a rather elegant plan for a four-hour charter: the lagoon early, while it is empty and clear, the caves in the middle of the day when the light is at its best and the lagoon is at its worst, and then wherever you like. The two halves of the trip want opposite hours, and a private boat is the only kind that can give them both.
