The first time I put my face in the water off Calanque d'En-Vau, I forgot to breathe through the snorkel and swallowed half the Mediterranean. Worth it. Below me a school of saddled seabream hung in a shaft of light, and the limestone wall dropped away into a blue I had no word for. We had sailed down from Marseille that morning, dropped the hook on a sandy patch, and I had not expected the snorkelling to be the highlight of the whole Provence leg. It was.
If you are cruising between Marseille and Cassis with a mask aboard, this stretch is the best in-water wildlife you will find on the French mainland. Here is how I learned to make the most of it.
What is actually down there
The Calanques National Park, created in 2012, is France's richest Mediterranean marine protected area. The numbers behind it are genuinely large: the park's underwater zone shelters more than 1,000 fish species and Posidonia seagrass meadows covering roughly 1,200 hectares, which provide habitat for an estimated 80 percent of local marine life. Sixty species are listed as marine heritage.
For a snorkeller, that abundance translates into a reliable cast of characters. On almost any rocky drop you will see:
- Saddled seabream and two-banded seabream in loose schools
- Ornate wrasse and peacock wrasse picking at the rock
- Octopus tucked into crevices (look for a tidy pile of empty shells outside a hole)
- Sea urchins by the thousand, so watch where you put your feet
- The occasional grouper if you are over deeper coralligenous reef
Seahorses turn up in the Posidonia, though I have only ever seen one, and I nearly missed it. The dusky grouper is the prize. They were hammered by spearfishing for decades and are slowly coming back inside the no-take zones, where fishing is banned outright.
Where to get in the water
You do not need to go far. Some of the best snorkelling is right on the rock walls where a calanque narrows, in 3 to 8 metres, where light still reaches the bottom and fish congregate.
If you are anchored, I prefer to swim from the boat rather than land. The eastern calanques near Cassis (Port-Miou, Port-Pin, En-Vau) get crowded with day boats by mid-morning in July and August, so an early arrival pays off. Closer to Marseille, the Sormiou and Morgiou inlets are quieter and just as rich. Both Sormiou and Morgiou have small huts (cabanons) ashore and a handful of restaurants, but no fuel or water, so arrive self-sufficient.
Visibility is the thing that makes or breaks a session. Locals reckon May to October gives the clearest water, with the best days running 25 to 35 metres of horizontal visibility. After a strong mistral churns the surface that can collapse to a murky few metres for a day or two, so I time my swims for the calm spell that follows the wind, not during it. If you want the full picture on getting between these inlets under sail, my notes on exploring the calanques of Marseille and Cassis by boat cover the approaches and the anchoring restrictions.
Water temperature, and what to wear
Do not assume the Med is bath-warm. Surface temperatures here swing from about 13 degrees in winter to 25 degrees at the August peak. Even in summer, a thermocline can sit a few metres down, and you feel it as a cold curtain when you free-dive past it. I snorkel in a 2mm shorty from June, and in a 3mm full suit either side of the season. A thin suit also saves your back from sunburn, which is the injury that actually ends most snorkelling days.
The seabed you must not touch
Here is the part most visitors get wrong. Those green-brown meadows waving below you are Posidonia oceanica, a seagrass found only in the Mediterranean. It grows from about 1 metre down to 40 metres in clear water, and it grows agonisingly slowly, a few centimetres a year. A single anchor drag can gouge a scar that takes a century to heal.
That is not just an ecological point, it is now the law. France bans vessels over 24 metres from anchoring on Posidonia, with fines that can reach 150,000 euros. Smaller boats are not exempt from the spirit of it. The rule for everyone is simple: anchor on the pale sand, never on the dark grass. Reading the seabed by colour is a skill worth practising from the bow before you let the chain run. I keep the Posidonia anchoring ban in France bookmarked, because the protected zones keep expanding and the boundaries are not always obvious from the water.
When you snorkel over a meadow, float, do not stand. Standing on Posidonia snaps the leaves and crushes the rhizomes underneath. The same logic applies to the wider question of where you drop the hook, which I dug into in my guide to low-impact anchoring for wildlife.
Practical kit and a few rules
The park has a zoning system, and a handful of fully protected no-take reserves where you cannot fish, anchor, or sometimes even swim. The Riou archipelago zones are the strictest. Check the current park map before you plan, because the boundaries shift and the fines are real.
Beyond that, keep it simple:
- Carry a dive flag float if you are swimming away from the boat, day-boat traffic here is heavy
- Never feed the fish, it changes their behaviour and concentrates them unnaturally
- Leave the spear at home inside the park, spearfishing is banned in the marine zones
- Take photos, take nothing else, removing shells, urchins or anything living is prohibited
How a typical session runs
Once you have the bay and the conditions, the routine is the same every time, and getting it right is the difference between a frustrating splash and a proper hour in the water.
I anchor on sand, in 4 to 8 metres if I can, somewhere the wall of the calanque comes up steep. Then I rig the snorkel gear in the cockpit before I get in, because faffing with a leaking mask while treading water in 6 metres is how people swallow seawater and give up. Spit in the mask, rub it round, rinse, and it will not fog. A cheap pair of fins makes a huge difference to how far you can range and how easily you can hold position against a light current.
From the boat I swim along the rock wall rather than out into open water. The wall is where the life is: the fish shelter against it, the octopus dens are in it, and the light bouncing off the pale rock makes everything visible. I free-dive down a few metres now and then to look into the cracks, but most of the spectacle is in the top 5 metres where the sun still reaches. An hour is plenty. Cold and sunburn, not lack of fish, are what end the session.
The best single tip I can give: go slowly and stop moving. Hover, breathe quietly, and wait. Fish that scattered when you arrived drift back within a minute or two once you stop thrashing about, and an octopus that has pulled into its hole will sometimes ooze back out if you simply hang still above it.
Why I keep going back
The Calanques work because they are protected, and you can feel the difference the moment you cross into a no-take zone. The fish are bigger, bolder, and there are simply more of them. It is a living argument for marine reserves, made visible to anyone with a five-euro mask.
I have snorkelled a lot of the French coast. Brittany has its own cold-water magic, and the Atlantic islands have their seals and seabirds. But for sheer in-water spectacle reachable from the deck of a small boat, nothing on the mainland beats a flat-calm morning in En-Vau with the sun cutting down through 8 metres of clear water onto a wall of fish. Bring the mask. Anchor on the sand. Float gently. The Mediterranean will do the rest.
