There is a stretch of water off the western tip of Finistere where the Atlantic meets the rocks of the Pays de Leon, and the French gave it a name that means business: the Iroise. It is one of the most heavily lit pieces of sea anywhere, because it is one of the most dangerous, and the keystone of the whole system, for a boat working the inshore route, is the slim grey tower of the Phare du Four. Everything else on this coast arranges itself around it.
I have run the Chenal du Four enough times to have a relationship with these lights. They are not picturesque to me so much as functional, and that is exactly why I have grown fond of them. Each one is telling you something you need to know.
Standing on its lonely rock
The tower stands off the Saint-Laurent peninsula at Porspoder, between the coast of the Pays de Leon and the Roches d'Argenton, planted on bare rock in the open sea. Construction began in April 1869 and the light first shone on the night of 14 to 15 March 1874. It is 28 metres tall, a single elegant shaft of granite, and it was automated in 1993 when the last keepers left. In 2017 it was listed as a national monument, recognition of a tower that had earned its place by sheer endurance.
It belongs to the grim brotherhood the Bretons call the hell lighthouses, the ones built far out on isolated rock where a keeper's relief could be weeks late in bad weather and the sea broke clean over the lantern. Sail past the Phare du Four in any swell and you understand the nickname without anyone explaining it.
Why the Iroise is so heavily lit
The reason for all this granite is simple. The Iroise is a maze of rock, strong tide and Atlantic swell, the gateway between North Brittany and the Bay of Biscay. The only sensible inshore routes through it are the Chenal du Four, running north to south inside Ushant and Molene, and the Raz de Sein further south. Both are tidal gates, and both demand precise timing on High Water Brest, which is why I never treat them casually. If you are planning the run, the Chenal du Four and Raz de Sein passage is the piece to read first, because the lights only make sense once you understand the tide they sit in.
The Chenal du Four reaches 4 to 5 knots of stream in places and the Raz de Sein up to 6 knots at springs. A boat doing 6 knots through the water has no margin against a foul stream like that, so the lights are not decoration. They are the marks you steer by to thread a moving, rock-lined channel at the one hour of the day it is safe to do it.
The supporting cast off Ushant
The Phare du Four anchors the southern approaches, but the Iroise holds a whole constellation of famous towers, most of them gathered round Ushant a few miles offshore.
La Jument is the celebrity, raised on a rock about 300 metres off the south-west of the island. It took from 1904 to 1911 to build because the sea kept stopping work, and it stands 47 metres tall. This is the lighthouse from the photograph everyone knows, a wave swallowing the entire tower while a keeper stands in the doorway. Pass it in a calm and the scale is deceptive; pass it in swell and the picture explains itself.
The Phare du Creac'h, on the western point of Ushant, is reckoned the most powerful lighthouse in Europe, its black-and-white bands a daymark for miles and its beam quoted at around 30 miles at night. And the Phare du Stiff, on the high eastern side, is the patriarch: designed by Vauban, built around 1695 and first lit in 1700, which makes it one of the oldest working lighthouses in France. Three towers, three centuries of lighthouse history, all visible in an afternoon if you take the offshore route round the island.
Anchoring to take it in
If you want to sit and look rather than rush past, a couple of options open up in settled weather.
- The Baie de Lampaul on the south side of Ushant gives shelter in westerlies and a dinghy run ashore, within sight of Creac'h. The holding is patchy and it is no place to be in a blow, so I treat it as a fair-weather stop with an anchor watch.
- L'Aberwrac'h, just north of the Iroise proper, is the comfortable base for the whole region. From the river you look out towards Ile Vierge, and it makes a fine place to wait for your tidal window. The wider North Brittany cruising guide covers the abers and the bolt-holes you fall back to here.
For the bigger picture of how all these towers string together along the granite coast, the Brittany lighthouses overview sets the Iroise lights in their wider company.
A protected sea, not just a hazard
Worth knowing as you sail through: the Iroise is not just a navigational hazard but a protected one. It was designated France's first marine nature park, a recognition that the same rocks and currents that wreck ships also shelter an extraordinary spread of seabirds, seals and kelp forest. The lighthouses and the wildlife share the ground. You will often see grey seals hauled out on the rocks around the Molene archipelago, and the seabird colonies on the offshore islets are nationally important.
For the cruiser this changes very little in practice, beyond the usual courtesies: give hauled-out seals a wide berth, keep wash down near nesting islets, and do not land on the bird reserves. But it adds a dimension to the passage. You are threading a working lighthouse system through a living marine park, and the two have coexisted here for a long time. The towers were built to keep ships off the same rocks the seals now use, and on a quiet morning in the Chenal du Four the whole thing feels less like a hazard course and more like a place that has made its peace with the sea.
Learning the lights by eye
The real reward of all this is that the Iroise becomes legible at night. The Phare du Four marking the southern reach of the channel, the long sweep of Creac'h, the steadier flash off the Stiff: each tower has its own character, and once you know them you can place yourself on the chart without a glance at the plotter. I still cross-check the almanac, because characteristics get changed and nominal ranges flatter what you actually raise in the haze that so often hangs over this water. But reading the lights is the oldest pilotage on the coast, and on a black night off Finistere it is the skill that turns a tense passage into a measured one.
Time your Chenal du Four passage right, in settled conditions and a modest coefficient, and the Phare du Four slides by at the pace of a slack tide while the Ushant lights stand off to the west. It is one of the great sails in France, made navigable by a handful of granite towers that have been keeping ships off the rocks since long before any of us were born, and that still do the job every single night.
