Surface data from Open-Meteo, visibility from Copernicus Marine / NOAA CoastWatch.
How the score works
Every spot gets a composite score out of 10. Satellite Secchi depth is the dominant factor (0-10 base), multiplied by surface condition penalties, then safety-capped.
Secchi depth from Copernicus Marine satellite data (NOAA VIIRS fallback). 20m+ is gin clear. Below 3m you can barely see. This is the dominant factor in the score.
Flat water is ideal for entry and exit. Above 1.2m waves create surge underwater and dangerous shore conditions. Above 2m the cap kicks in.
Calm conditions mean better surface visibility and safer boat diving. Above 25 km/h most dive operations cancel.
20-28°C is ideal. Below 15°C needs a thick wetsuit, below 10°C a drysuit. Comfort affects bottom time and enjoyment.
Frequently asked questions
How often is this updated?
Surface conditions (wave, wind, temperature) update every 3 hours from Open-Meteo. Underwater visibility data updates daily from Copernicus Marine (primary, 1 to 2 day lag) and NOAA VIIRS (fallback, weekly composites).
How is the diving score calculated?
A multiplicative penalty chain: Secchi depth base (0-10) multiplied by wave height, wind, current, water temperature, rain, atmospheric visibility, and tide factors. Safety caps prevent inflated scores when conditions are dangerous. A dawn bonus rewards early morning calm dives.
What does 'visibility data unavailable' mean?
Satellite ocean colour data has gaps near coastlines (land masking) and during cloud cover. When Secchi depth data is missing, the score defaults to 5.0 (neutral) and is driven entirely by surface conditions. Spots with persistent gaps are typically very close to shore.
What types of diving does this cover?
Freediving, spearfishing, and recreational scuba. The scoring optimises for conditions that suit all disciplines: clear water, calm surface, manageable current, and comfortable temperature.
Where does the visibility data come from?
Copernicus Marine Service (primary) blends multiple satellites into a gap-free daily product with direct Secchi depth measurement. NOAA CoastWatch VIIRS (fallback) derives Secchi from Kd490. Both at approximately 4km resolution, so conditions can vary at the waterline.
Are these the same spots as the surf leaderboard?
Yes, the same 260 coastal spots. Great surf days and great diving days are often opposites: divers want flat, calm, clear water while surfers want swell and energy.
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