The best hour to dive, scored — not guessed
Every site gets a 0–100 score, recalculated hour by hour, built from real current, tide, weather, and swell data — not a generic marine forecast. Here's exactly how it's calculated, and where the data comes from.
Four signals, one plot
A dive window is scored from meteorological and hydrological data read together, not from a single forecast number. Here is what a tidal day looks like when all four are drawn on the same timeline — the tide swinging through two highs and two lows, the current running hardest between them and going slack shortly after each turn, a distant swell decaying, and the afternoon sea breeze building on top of it all.
Meteorological and hydrological conditions
One tidal day at a coastal site — four signals, one plot
Meteorological
Swell
0.8–1.4 m
30% with wind
Wind
5–19 mph
30% with swell
Hydrological
Tide
±1.1 m
10% of score
Current
±1.6 kn
60% of score
H high water · L low water · S slack. Each trace is scaled to its own range — mph, metres and knots share no axis, and forcing one on them would flatten three of the four into straight lines. The ranges are in the key above; the app shows them in your own units.
An illustration of the real in-app conditions chart, drawn from tidal and sea-breeze physics rather than a live feed — the live version reads a specific site's forecast and needs an account.
The real math, not a black box
Every score breaks down into named components with real weights — click any window in the app and the explainer shows the same breakdown.
Current & slack carry the most weight
60% of the score (65% on Great Lakes sites) — the single biggest factor in whether a dive is comfortable or a fight. Scored against predicted slack timing and peak velocity, not just a daily average.
Weather and swell, scored together
30% of the score (35% on Great Lakes sites). Wind, swell height, and swell period combine — a 3 ft swell at 16 seconds carries more energy than 5 ft at 6 seconds, and the score accounts for that, not just wave height alone.
Tide height rounds it out
Up to 10% of the score on tidal sites — skipped entirely on the Great Lakes. Water level and current already share the same wind-driven mechanism there and would double-count the same signal.
Every data source, named
NOAA WAVEWATCH III for ocean coastlines, Great Lakes-specific GLOFS/GLWU models with ice-season awareness, and Copernicus Marine for international coverage. Not a generic marine forecast API.
The water where you dive decides what matters
Those weights are the baseline, not the verdict. Every diver gets four sliders under Settings → Preferences → Scoring weights, and they change how your windows are ranked — because what ruins a dive in one place barely registers in another.
Pacific Northwest
Enormous tidal exchanges drive hard current through every pass and narrows, and slack lasts minutes. Timing the turn isn't a detail here, it's the dive — so Tide & Current should carry most of your score and weather can come second.
Warm-water reef
Barely any tidal current to plan around, so the real question is whether the surface is workable at all. Wind and swell decide that — which is exactly what the Photographer preset leans into.
The Great Lakes
No tide to weigh at all. The engine drops tide to 0% on Great Lakes sites and shifts that weight onto wind-driven current and wave height. Your sliders then set how much those two matter to you.
Four sliders, always adding up to 100%
Slack current timing and tide height
Wind, rain, visibility, and sea state
Avoid recently visited sites
Match your preferred diving times
Or start from a preset built around how you actually dive, then fine-tune from there — moving any slider yourself just switches you to Custom.
Weights are free for every signed-in diver — they're part of tuning the engine, not a paid add-on.
One free look, then it's an Advanced feature
Basic (free) gets one look at Explore scoring. Advanced unlocks the full engine — every site, every window, every hour — plus the 7-day extended forecast.
See exactly why, every time
Every recommendation has an explainer — the component scores, the contributing factors, and the warnings — not just a number you have to trust.
Stop guessing where to dive, and when
Create a free account and see your first Explore score — no card required.