Tides and currents
Tide and current data drives a lot of what Submarius does — the verdict, the bite-score, the water-clarity penalties — but it’s also surfaced directly as a feature so you can plan around it.
What’s shown
For any coastal location:
- High and low tide times for the next seven days
- Tide range (height between consecutive high and low)
- Current rising / falling / slack state at any selected hour
- Spring vs neap indicator (within ±3 days of new/full moon)
- Hourly water-level graph with the times of all the day’s slack windows highlighted
Currents are shown where NOAA publishes prediction data (US coastal, including Alaska and Hawaii). Outside that coverage we display tides only.
Source
- Tide predictions — NOAA Tides & Currents, via the predictions API. NOAA’s harmonic-analysis model is the gold standard and we use it directly.
- Currents predictions — same provider, where available.
- Sea-level observations (where stations exist) for the live comparison.
For non-US locations, we fall back to global tidal modelling from Open-Meteo Marine.
Why this matters for the verdict
Tide stage feeds three other features:
- Water-clarity model. Falling tide in an enclosed bay flushes sediment-laden water out; rising tide brings cleaner offshore water in. The clarity penalty for tide stage depends on the coastline geometry classification (open / semi-open / enclosed) of the location.
- Bite score. Most species feed actively on moving water; activity drops near slack.
- Diving access. At many sites, slack is the only safe time to enter the water — strong currents during peak flow can be dangerous for shore divers.
The verdict integrates these without forcing you to read the tide chart yourself, but the chart is one tap away.
Spring tides
Spring tides (within a few days of new and full moon) produce the largest tidal range and the strongest currents. For some activities that’s good (more bait movement, hungry predators); for others it’s bad (too much current, too much sediment churn). The app indicates spring state and the verdict adjusts accordingly per activity.