spearo sea-state engine: consensus of up to 6 models + satellite clarity (ZSD) + buoy-bias checks
Freshness
Re-read every hour, per coast
Compiled by the spearo sea-state engine · How it works →
The verdict comes from seven water factors and hard safety gates — not ten tabs. Go or stay.
How we score the water
Our own model
Our own forecast engine — not a third-party widget. It weighs these water factors into one go-or-stay verdict for this coast; the 0–10 dial is that verdict, read out as a number.
01
Swell & wave memory
Height, period and direction of the swell, plus the wake of recent storms — an old storm still stirs the water, and the engine remembers.
02
Wind & gusts
Speed and gusts, hour by hour — wind speed and an onshore push chop the surface and cut visibility.
03
Tide phase
Timing and range of the tide, calibrated per coast — big spring tides pull the verdict toward caution.
04
Water temperature
Sea-surface temperature — sharply cold water vetoes a green verdict.
05
Currents & outflow
Direction and drift of the current — it pushes you, and it drags turbid coastal water across where you dive.
06
Rain runoff & air clarity
Rain muddies the water inshore through land runoff, while fog and haze cut visibility at the surface.
07
Coast shape & exposure
How the coast faces the swell — a sheltered cove keeps the water clean; an exposed, head-on point takes a penalty.
Safety gates
Thunderstorm forecast — an instant red, no exceptions.
An official warning (MeteoAlarm / IPMA) — yellow, or red for the higher ranks.
Missing input data — a would-be green is capped to yellow rather than overstated.
Strong disagreement between forecast models — a green day is pulled back to yellow.
Night hours — where night spearfishing is banned by law the window is forced red; where it is legal (Australia outside NSW, New Zealand, South Africa) it is capped at yellow, never green.
It all folds into a single 0–10 score and one verdict: go or stay.
A forecast, not a guarantee — the sea has the last word.
Where to get in, where to hunt
Entry points with coordinates
Seabed relief — promising ground
This verdict — in your pocket. Open the app for the week's window.
point your camera
0 m
Surface
Wind, wave and the swell windows — when to go and the best hours.
spearo.app
no dataupdated 03:33
Castro Urdiales — solo, off the rocks
DON'T GO
don't go · wave 1.9 m (occasionally up to ~3.8 m)
wave 1.9 mwind 13, gusts 26 km/hsurge pounding the rocksvisibility ~1 m
What's missing? Tell us what you'd like to see — new spots, species, data or features. We read everything.
Your best window — with you. Forecast in your pocket.
point your camera
−10 m
The water column
Visibility and what drives it — post-storm clearing, river plume, temperature and the thermocline.
What it is
A marine instrument, go / no-go for solo hunting.
spearo.app folds wind, wave, swell period, visibility, tides, water temperature and risk into a single verdict — go to the spot or not. It computes 7 days ahead from open marine models (Open-Meteo, IPMA), with no sign-up and no accounts. Built for solo spearfishing off the rocks, where any mistake costs dearly.
Now live: 3016 spots across 406 stretches of coast — mainland Portugal, Madeira and the Azores.
This cape asks for dawn and a high-pressure day: as soon as the northwest breeze fills in, the day is over. Autumn is the best season, mild water and the Agüera running low. Sunset to sunrise is banned, and pollack cannot be taken from 1 January to 30 April.
tide
On springs the range goes past four metres and completely changes the access: near high water you get in off the rock without drama, and at low water you have to cross a long, slippery boulder field. On the ebb there is noticeable current along the cape, so plan your way back.
shelter
The cape rises at the foot of Monte Candina and faces north: the sector from 310° to 60° comes in whole and the worst heading, 340°, hits the wall with nothing in front. The massif blocks the south, so with a land wind the water sits still under the cliff.
conditions
This is some of the cleanest ground on the stretch: live rock, little sediment and, on a genuinely calm day, seven or eight metres of visibility. What pulls it down is the Agüera outflow in the Oriñón inlet right next door: with the river up, brown water clings to the shore.
hazard
Isolated place with no reliable phone coverage: you do not come here alone. Candina drops rock onto the beach and is a protected area with a vulture colony, so respect any path closures. The ground swell arrives without wind and washes the foot of the cape; if in doubt, do not go down.
access
You get there on the Sonabia road, park in the village and walk down to the little beach at the foot of the mountain. From there you swim east along the base of the cape, three or four hundred metres. There is no intermediate exit along the cliff: you come back to the same sand.
Cliff and rock to the east; very exposed, advanced.
Cantabria has no weekday closure, so any day works, but in August the Arenillas campsite fills the beach and it pays to start at dawn. The best season runs June to October; pollack, remember, is closed from January to April and then it is two fish only.
tide
With over four metres on springs, the Cerdigo ledges are left dry at low water and the approach turns into a long walk over weed-covered stone that is as slippery as soap. In some coves you can only get in comfortably near high water; check the table before you go down.
shelter
The stretch from Cerdigo to Islares, with Arenillas beach in the middle, faces north-northeast and takes everything that comes down from 310° to 60°. The rocky point at Cerdigo cuts some of the west and leaves usable coves, but with a northerly sea the whole coast breaks against the ledges.
conditions
The drop-offs along this coast hold visibility well, five or six metres on a decent day, because the bottom is rock rather than loose sand. What spoils it is the Agüera, which flows out at Oriñón a little to the west: after a spate the brown water runs this far.
hazard
Over the ledges the ground swell explodes without the wind warning you, and the galerna drops out of the northwest in a matter of minutes. Access runs off the N-634 and across some private land: ask permission and do not leave the car on the road. The second-class licence is compulsory.
access
Park up on the top, by Cerdigo or at the entrance to Islares, and drop down short tracks to the coves; there are several, and not all have a comfortable exit. The safest is to get in over the Arenillas sand and swim east, two or three hundred metres out to the rock.
Rocky shore to the east; coves and drop-offs, rich grounds, exposed to the NW.
The thing is to get in early, before the fleet goes out and the harbour mouth fills with traffic, and to make the most of autumn, with the water still at seventeen or eighteen degrees. Sunset to sunrise is banned across Spain, and pollack is off limits from 1 January to 30 April.
tide
With a four and a half metre spring range, the rock platform at the foot of the castle dries out at low water and shows you where to get in. On the ebb there is a clear rush between the Santa Ana islet and the bridge: if you cross it, do it at slack water.
shelter
The point that carries Santa Ana castle and the church faces north, with the bad sector between 310° and 60°: the 340° northwest comes in unchecked. The harbour breakwater to the southwest blocks the land wind, but sea from the first quadrant wraps around the point anyway.
conditions
The rocky ground below the castle has cracks between ten and twenty metres where conger and the odd grouper hide; with a flat sea you see well there. What clouds it is the harbour churn and the town's runoff after rain: two dry days and it clears again.
hazard
You are right by the mouth of a working harbour: fishing boats and pleasure craft come and go, and you must leave 300 metres to professionals at work. Carry the buoy high and red or orange, and check where the port zone ends, because inside it spearfishing has no business.
access
You go down from the Santa María church promenade over the stone ramps to the water, on the eastern face of the point; the rock is slick with green slime. The other option is to get in over the Brazomar sand and swim towards the castle, four or five hundred metres close to the shore.
Rocky ground below the castle; grouper and conger in the cracks (10-20 m), exposed to the N.
From June to September these are lifeguarded beaches with a buoyed bathing zone: the only option is to get in at the very first hour, and even then outside the markers. The rest of the year any daylight hour works, with the bonus that winter water is clearer.
tide
At a spring low the rock benches at both ends of Ostende come out and you walk to the edge without wetting your knees. At a spring high the sand shrinks to a strip against the promenade wall and you have to get in from the steps.
shelter
The two town beaches sit inside the Castro bight: Santa Ana point and the harbour cover the east, and the town itself cuts the south. What comes straight in is north and northwest, and with that sector the rocky ends of Ostende break and there is nothing to be done.
conditions
It is a shallow spot, three to eight metres, with low rock and weed beds at the ends: it works for learning and for your first fish, not for looking for depth. Suspended sand rules here: after two calm days you get four or five metres, with any waves you get one.
hazard
The risk here is not the sea, it is the people: swimmers, paddleboards and rod anglers on the points. Do not enter the buoyed area, carry a red or orange float and never get more than 25 metres from it. After a storm the town's overflows dirty the water; better to wait.
access
You park along the Brazomar promenade or near the Ostende playing field and drop to the sand by ramps and steps, all easy. Walk to whichever rocky end suits the wind and get in off the low stone; with any waves, get in and out over the sand and not the rock.
Rocky ends of the town beaches; semi-sheltered, good for beginners.
SOLO is the biggest risk: underwater you can black out from lack of oxygen silently and fatally, with no one around. Solo is never truly «safe». Below are the best weather windows; carry a buoy, tell someone your plan and exit time, and any doubt — don't go.
One morning glance — and you know.
point your camera
≈
Surfacing
Cameras, map and reference — to hand as you come up.
Live cameras, map & reference
Cameras · live
Look at the water right now.
Check the cam BEFORE you leave. Foam, brown/green murk, or waves washing the entry rocks = No-go. At night/in fog the cam is useless — treat it as «unknown», NOT «green».
✓Spearfishing licence mandatory; the AUTONOMOUS COMMUNITY issues it (not the State) and it is valid in the exterior waters of the whole coast. Free-diving only — scuba is banned (, art. 3).
✓Spearfishing catch may not be sold or traded — it is non-commercial fishing ().
✓Night prohibited: spearfishing only in daylight (sunset to sunrise not allowed) — , art. 16.d.
✓Marker buoy MANDATORY: mark your position with a clearly visible buoy and stay within 25 m of it — , art. 15.
✓Never keep the speargun loaded out of the water — , art. 16.a.
✓Keep at least 300 m from professional fishing vessels that are working — , art. 12.b.
✓The state act (, art. 16) bans, for spearfishing: a loaded gun out of the water; explosive/electric points and lamps (hand torches excepted); underwater scooters; night — from sunset to sunrise. Plus art. 12 b), d), e): 300 m from professional fishing vessels, light as an attractant, poisons/explosives. A ban in a PARTICULAR reserve, port or beach comes from that place's OWN instrument (the reserve's order, the autonomous community's rules, the port authority) — see the no-take zones on the map and your community's rules.
✓Min. sizes by ( + + EU 2019/1241): sea bass 42 cm (rec.) / 36 cm / 25 cm Mediterranean / 22 cm Canaries; gilthead bream 20 cm and white seabream 23 cm in the Mediterranean (EU 2019/1241); grouper 45 cm. See your zone's species card.
✓Only species in Annex I of may be taken; keeping, landing or transporting undersized specimens is prohibited.
✓The licence needs a medical fitness certificate for free-diving and civil-liability insurance (or a federative licence, which includes it). Mandatory in the Basque Country/Murcia/Asturias/Galicia; the federative licence covers it in Galicia/Balearics/Cantabria; the Canaries and Andalusia do NOT require it for the individual licence (a responsible health declaration). Minimum age generally 16 (14 in Andalusia).
Safety protocol
Sets: watch the wave trains ≥15 min before entering; Hmax ≈ 2×Hs, the wash can run 50 m past the foam line. A lull >10 min with period >12 s = a big set «overdue», do NOT enter; enter right after a full set passes and re-check at minute 30.
Exit FIRST: find your exit AND a backup before entering. On a rocky/boulder shore a 0.5 m rise in swell can make the exit impossible — getting pinned/unable to climb out is the main killer.
Headland rip: prominent points often have a permanent topographic rip regardless of the model — locate it, enter/exit on the windward side, never swim against it.
Cold: wetsuit per the SST chip; the first shiver = a metabolic surge and a drop in breath-hold → get out at the first steady shiver. Cap the session at 45–60 min below 15 °C.
Solo discipline: buoy up; tell someone the spot and exit time; conservative breath-hold (never push it in cold/murky/surfy water); visibility <3 m — don't enter.
Afternoon wind: on many coasts the wind builds from midday — plan to be out of the water by midday; the chop builds — get out.
UV 11:00–15:00 (UVI ≥6): sunscreen and cover up on the surface interval.
Solo is a fundamental risk (hypoxic blackout with no buddy). Any doubt = No-go.
Local guide · Castro Urdiales
Spearfishing in Castro Urdiales: spots, seasons and rules
Updated 2026-07-09 · By Oleksandr, spearfisher
Spearfishing in Castro Urdiales is shore-entry rock hunting on an exposed Cantabrian coast. The practical split is simple: Ostende / Brazomar is the cautious beginner option, Punta de Santa Ana has cracks below the castle, Cerdigo / Islares gives coves and drop-offs to the east, and Cabo de Sonabia is advanced cliff-and-rock ground. The coast faces north, with the bad sector from northwest through northeast, so do not treat a calm-looking town beach as proof that the points are safe. In Cantabria, the 2nd-class licence enables spearfishing, and the Cantabrian-Northwest size table applies.
TL;DR
Castro Urdiales is a north-facing Cantabrian rock coast, with the worst sea from northwest to north.
Ostende / Brazomar is the softest entry because it sits on semi-sheltered rocky beach edges.
The legal setting is Cantabria, and the species sizes are Cantabrian-Northwest: sea bass is 42 cm.
Best legal spearfishing spots near Castro Urdiales
These shore-entry zones should only be used with settled sea, a visible buoy and confirmed local limits.
Spot
Type
Depth
Level
Access
Notes
Ostende / Brazomar rocks
Rocky beach edges
Shore rock in shallow water
Careful beginner
From the beach edge, away from bathers
Semi-sheltered and the easiest learning choice when bathing areas are not busy.
Punta de Santa Ana
Rocky ground below the castle
Mid-depth cracks
Intermediate
Shore entry with a clear exit route
Grouper and conger are noted in the cracks, but the point is exposed to the north.
Cerdigo / Islares
Rocky shore to the east
Rock ledges and drop-offs
Intermediate
From the cove, away from bathing areas
Rich ground, exposed to northwest swell, so use it only with a settled sea.
✓There is no fixed national catch cap (, art. 5 delegates it to the communities); the standard is 5 kg/person/day, with 1 specimen allowed not to count (Canaries — Decreto 182/2004, art. 38.3; Murcia; Galicia; Basque Country). Protected species have per-piece quotas.
✓Only a harpoon is allowed — hand-held or mechanically propelled, with one or several points (, art. 14.1). Carrying spearfishing gear and underwater breathing equipment aboard AT THE SAME TIME is prohibited (art. 14.2) — an offence in itself, even if you dived on a breath hold.
✓Spain is not one jurisdiction. The licence is issued by a coastal autonomous community, and you must comply with the rules of the administration on whose littoral you are in the water: «debiendo cumplir la normativa establecida por la administración en cuyo litoral se realice la actividad» (, art. 13). Interior waters — inside the straight baselines: bays, coves, rías, the whole coastal strip — are the community's competence; exterior waters are the State's. So the age, the days of the week, the distances and the are found in your community's act, not in the state one.
✓Cantabria: the spearfishing licence is issued by the Gobierno de Cantabria — the 2nd-class licence enables spearfishing (sede.cantabria.es).
✓Cantabria recognises issued by the State or other communities: in its waters they «have full validity» (Ley 1/2021, art. 27.7).
✓Cantabria: the right to spearfish comes with the 2nd-class licence (Decreto 45/2002, art. 3.b); only a harpoon, hand-held or mechanically propelled, is allowed (art. 7); the buoy is red or orange and clearly visible (art. 8). The cap is 5 kg per licence per day, and from a boat carrying more than five licences, no more than 25 kg per boat per day (art. 9.1). Selling the catch, autonomous diving equipment, fishing between sunset and sunrise, port and prohibited/reserved areas and taking cephalopods are all prohibited (art. 14). Barred within 100 m of beaches and other bathing places, a distance that rises to 250 m from May to October (art. 15.b).
⛔ Seahorses (Hippocampus) — protected (RPE).
Rules change and are REGIONAL. Before heading out, check with the competent autonomous community (licence) and the min-size table in force.
What are the licence, conditions and species essentials?
Cantabria issues the spearfishing licence, and its 2nd-class licence enables the activity. Cantabria also recognises valid recreational sea-fishing licences from the State or other autonomous communities. National rules still apply: freediving only, daylight only, no sale of catch, no loaded speargun out of the water, and a visible buoy within 25 m. The caladero is Cantabrian-Northwest: sea bass is 42 cm, gilthead 19 cm, black seabream 23 cm, conger 58 cm, and octopus has a 1 kg minimum. Atlantic pollack has a recreational closure from January 1 to April 30.
FAQ
Is Castro Urdiales good for beginners?
Only the Ostende / Brazomar rocky beach edges fit that role, and only in settled sea.
Which swell direction is bad?
Northwest to northeast is the bad sector, with north-northwest the worst axis.
Do I need a licence?
Yes. In Cantabria, the 2nd-class licence enables spearfishing.
What is the sea bass size here?
In the Cantabrian-Northwest caladero, sea bass is 42 cm.
Are there protected species?
Seahorses are protected, and undersized catch must not be kept.
Spain
