Two pictures per hazard, because there are two questions.
What does this place look like? is answered by a photograph. Which way do I
go? is not — a satellite image cannot draw the choice, and the drawing cannot make the
place feel real. So both, side by side, for every entry.
Every hazard here was compiled from prose that already existed: cruising guides, forum
threads, sailing logs, spearfishing sites — in Greek, Spanish, French and Basque. No survey.
01
Agriógatos reef
Corroborated
Ithaca — Marmagkas (Agios Nikolaos) bay, N side of the entrance
also: Attention reef · wild cat
38°28.937′N20°40.597′E
50 m wide · 241 m offshore
50 m wide reef on the north side of the bay entrance, roughly 250 m offshore and 287 m NNE of the islet. Unmarked: no buoy, no cardinal, nothing on the water to see.
Avoiding actionEnter the bay passing SOUTH of the islet — there is 235 m of clear water between the islet and the shore. Do NOT pass north of the islet: that route threads the 287 m gap between the islet and the reef, and it is the one boats hit.
Hendaye → Saint-Jean-de-Luz — off the Corniche basque
also: Les Couteaux du Diable · Briquets · Erretas
43°23.732′N1°44.980′W
1000 m wide · 3 m over it · 2000 m offshore
A plateau of long rocky slabs 2 km off Hendaye, depths 3–12 m, several of which «émergent (à basse mer) ou sont justes sous la surface». Spans roughly 1,000 m with multiple rocky heads. Straddles the coastal route Hendaye → Saint-Jean-de-Luz. It has four names — Erretas (ES/EU), Les Couteaux du Diable and Les Briquets (FR) — and no chart or database carries them all.
Avoiding actionJoin Cabo Higuer light to the Biarritz light and stay north of that line. It is a visual transit — both lights are in sight — and it clears Las Erretas by 1,449 m and Belharra-Perdun by 1,313 m in one stroke. To enter Saint-Jean-de-Luz you must cross it; do that east of Belharra.
Drawn from OpenStreetMap (ODbL) + published positions
Where this came from
Coordinates published by the source
Transit rule: «si unes una línea entre el faro de Higuer y el de Biarritz y navegas al norte de ello, las evitas» — verified by computation (Briquets 1,449 m inshore of the line, Belharra 1,313 m inshore). Published in no chart or guide found.
masmar derrotero de Euskadi: «Tanto este canal como los pasos que dejan entre si las piedras que emergen de Les Briquets solo son abordables con buen tiempo, sin mar de fondo y POR CONOCEDORES DE LAS MARCAS.» — the guide states that local marks are required, and withholds them.
sea-seek.com publishes the position — but the whole entry is one line typed by one user («azertv») on 7 June 2019: «Attention à cette zone de hauts fonds qui couvre et découvre!» That single seven-year-old edit is the only published position for this reef anywhere.
latabernadelpuerto.com forum — «Y Erretas es un arrecife de bastante respeto… más de uno ya ha quedado allí»
mibaluma.blogspot.com log — marks it as a GPS waypoint in order to clear it
lechasseursousmarin.com — 2 km offshore, 3–12 m, slabs that emerge at low water
Google Maps carries the label «Les Briquets». OpenStreetMap has nothing under any of its four names.
Found by searching sailors' vernacular, not hazard nouns. Position inferred from prose («2 km du littoral») was 702 m wrong before the published coordinate was found.
Reef connected to Cape Elia, called 'infamous' in English sources. The Greek guide is more specific and adds a second danger the English sources omit: «Προσοχή στους υφάλους βόρεια του κόλπου του Αθερινού και μέσα στον ίδιο κόλπο δεξιά όπως εισέρχεστε» — reefs north of Atherinos bay, and inside the bay itself to starboard as you enter.
Avoiding actionFavour the port side going in — the Greek source puts the inner reef to starboard on entry. Anchor in deep water with a line ashore rather than working close round the cape.
The sandbank and silts at the north end of the canal continuously change shape. Charted depths go stale between surveys. Three groynes marked by yellow buoys.
Avoiding actionFollow the buoyed channel exactly. Do not trust charted soundings here — they describe a seabed that has since moved.
River bar. The Santiago beach sand spit has joined the counter-dike and dries at major low waters. The whole bight is very shallow and the sea builds over it in swell.
Avoiding actionThis is a conditional hazard, not a fixed one. Safe in calm at half tide, breaking and lethal on the ebb in northerly swell. Cross near high water, never on an ebb against swell.
Urrugne — 2.5 km NW of the baie de Saint-Jean-de-Luz
also: Belharra
43°24.617′N1°43.133′W
16 m over it · 2500 m offshore
Shoal rising to 14–18 m, 2.5 km offshore between Socoa and Hendaye. In big NW swell it raises a breaking wave of 8 to 15 m. It does not break most years at all — before the breakwaters were built it swallowed vessels moored between Bidart and Guéthary.
Avoiding actionThe chart shows 16 m and nothing else, so on 360 days a year this is open water. On the wrong day it is a 15 m breaking wave over your route. Check the swell forecast, not the depth.
River bar at the Adour mouth, now trained between jetties. Between 1773 and 1814 it wrecked six ships a year. More than two thirds went ashore on the north side — there is a dominant current at the mouth setting vessels that way.
Avoiding actionA trained bar is still a bar. Cross on the flood, never on the ebb against swell, and allow for the set toward the north bank — that is where two thirds of the wrecks ended up.
Rocks on the inshore side of the freu from Les Briquets; some emerge at low water. Published waypoint at its northern edge: 43º 23,279'N / 001º 44,925'W. The channel between Roches Noires and Les Briquets carries 3–11 m.
Avoiding actionThe freu is passable «con buen tiempo, sin mar de fondo y por conocedores de las marcas». If you do not know the marks, you are not one of those people — go outside Les Briquets.
The seabed from Gaztetape beach to Punta Irruarriaundieta (1 M at 297°) is stone, with twelve rocky heads inside the 4–6 m isobath. Published waypoint 43°18.576'N 002°12.947'W.
Avoiding actionStay outside the 10 m contour along this whole stretch.
The bay has four passes through the Socoa, Artha and Sainte-Barbe breakwaters — L'Illarguita, Herreca, Belhara Perdun and the eastern pass. Only L'Illarguita is recommended, and it is the only one usable at night. Depths run −15 m on the west side but only −8 to −9 m on the east.
Avoiding actionUse L'Illarguita. The other three are local knowledge, and one of them is named after the shoal.
Between the SW tip of Skorpios and Spartochori, Meganisi
also: Chiromyti · Cheiromyti
no published position — area warning only
Reef in the channel between the south-west tip of Skorpios and Spartochori, on the direct route from Lefkada to Meganisi. The Greek source: «Χρειάζεται ιδιαίτερη προσοχή αυτός ο ύφαλος διότι “αναδύεται” ξαφνικά και το βυθόμετρο δεν βοηθά» — it rises so abruptly that the depth sounder gives you no warning.
Avoiding actionDo not rely on the sounder here; by the time it reads, you are on it. This is a hazard you clear by position, not by instrument. Coming from Lefkada, stand off the south-west corner of Skorpios.
Broad shoal with a least depth of 13 m among soundings of 25–30 m, about 660 m north of Hendaye beach. Published waypoint 43º 23,7'N / 001º 46,2'W.
Avoiding action13 m is no threat to a keel. It is a threat to a sea: a shoal that abrupt in 25–30 m will stand the swell up over it. Treat it as rough water, not as a grounding risk.