Today — sit it out — wave, wind and surge pounding. 💧 Water should clear by Friday (~3d)
Sources & confidence
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.
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.
Safety gates
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
Leave your email — and the moment a window opens at Tateyama, we'll send the go / no-go verdict. Email is all we need.
What's missing? Tell us what you'd like to see — new spots, species, data or features. We read everything.
Wind, wave and the swell windows — when to go and the best hours.
The day is picked above, in the hero. Here are that day's windows, the hour-by-hour map and the trends. Tap a window to break down the conditions.
Visibility and what drives it — post-storm clearing, river plume, temperature and the thermocline.
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.
See all spotsRelief and bottom type, tides, and the depths of each spot.
The models set the window. Whether you go in is read only at the water: count the sets, watch the surge on the entry. If in doubt, you don't get in.
Scouted entries, coloured by today. The colour is the sea state at the spot, not a guarantee: the wash and a slippery entry you judge on site.
Open the seafloor mapWalk down a path beside the Banda dive shop to a small, calm beach that slopes gently over sand to about 7 m. The nearby boat reefs (Matsune, tyre reef, new reef, Karou-ne) sit at 11–20 m with soft corals and are reached by a 5-minute boat ride from Banda harbour. The beach is shop-managed; ask for permission and fees. Spearing not permitted in Chiba — check local rules.
Google MapsTied island reached on foot over a ~200 m sand spit; snorkel from the beach into the northern cove and rock reef, where small corals grow. The back (west) shore has fast current and surf and is not suited to swimming. A conservation fee is requested in the swimming season. Spearing not permitted in Chiba — check local rules.
Cameras, map and reference — to hand as you come up.
Japan: spearguns and scuba/hookah are banned for all recreational fishers nationwide (Fisheries Agency prefectural gear table); a hand spear (yasu) is allowed only in some prefectures (e.g. Okinawa, Kagoshima, Nagasaki, Kochi, Mie); abalone, lobster, octopus and sea urchin in fishery-right areas belong to the local co-op, and marine park zones are closed. Check current rules locally.
Wall / drop-off, cape rocky reef, 5–25 m, by boat. Spearing not permitted in Chiba — check local rules. Coords approx.
Google MapsSOLO 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.
Tateyama has rock entry points such as Banda, Okinoshima and Sunosaki. The Boso Peninsula's SW tip on Tateyama Bay — Banda's soft corals and Okinoshima's reef, southernmost coral communities on the Kanto coast, warmed by Kuroshio eddies. Below you'll find each spot (access, shelter and hazards) and today's forecast.
June–November; the Kuroshio keeps the water warm into late autumn, winter brings the north-west monsoon, and typhoons come August–October.
14–17 °C in February–March, 26–28 °C in August — 5–7 mm in winter, 3 mm in summer.
Rocky capes and reefs, Pacific swell and currents off the points. Spearguns and scuba are banned nationwide — only a hand spear (yasu), where the prefecture allows it; shellfish, lobster, octopus and urchin in fishery-right areas belong to the co-op.
Tateyama: Japan: spearguns and scuba/hookah are banned for all recreational fishers nationwide (Fisheries Agency prefectural gear table); a hand spear (yasu) is allowed only in some prefectures (e.g. Okinawa, Kagoshima, Nagasaki, Kochi, Mie); abalone, lobster, octopus and sea urchin in fishery-right areas belong to the local co-op, and marine park zones are closed. Check current rules locally.
