Submarius
A fishing app that actually tells you when to go.
Most fishing apps are dashboards: here's your wind, here's your tide, here's twelve species cards, good luck. Submarius replaces all of that with one number between 0 and 10: the Bite Score. It's the answer to the question every angler is really asking.
The Bite Score, in one sentence.
A 0–10 predictive score that aggregates tide stage, tidal range, moon phase, solunar major/minor windows, barometric pressure trend, wind, and water temperature. Updated hourly. Forecasted eight days out.
See a score of 8.4 at 6:30 AM tomorrow? That's the weekend clearing up. A flat 5 for three days straight? Fix the boat, tie flies, spend time with family. The fish aren't going anywhere.
Read the full methodology →Tide and moon, done right.
Solunar theory (the idea that fish feed most actively around moonrise, moonset, and the major/minor lunar transits) is either a cornerstone of your planning or pseudoscience, depending on who you ask. Submarius leans into the evidence that does exist and makes it easy to see:
- Tide turn windows. 90 minutes either side of a tide change, classic feeding cue.
- Strong tides (spring). New and full moons push the biggest water movement. Bait concentrates, predators follow.
- Moon position. Quarter-moon neaps mean weaker currents, sometimes good (clarity), sometimes not (less feeding).
The Bite Score already weights these for you. If you want to go deeper, tap the tide or moon tile and get the full chart plus a plain-English explanation of why it's contributing what it is.
8-day forecast, free tier ready.
See the bite trend curve across the next eight days as a single clean line graph. Which day is peaking? Which is flattening out? The auto-scaled Y-axis makes small changes visible instead of hiding them. Free users see today clearly; Pro unlocks the full eight-day outlook.
Community, without the noise.
Catch reports, leaderboards bucketed by species and geographic scope, and verified-scale catches for record hunting. GPS pins are optional and can be fuzzed on public posts, like every other spearo app should do.
Why not just use <other app>?
The incumbents (Fishbrain, Navionics) are built as reference databases with a weather overlay. They're genuinely good at species catalogs and depth-contour maps. We're not trying to replace those; we're solving a different problem: given all the data, should I go today? If you want that answer as a single number plus an explainable breakdown, this is your app.
Common questions.
A 0–10 score predicting how active fish will be at a given time and location. It combines tide stage and range, moon phase and position, solunar major/minor windows, barometric pressure trend, wind, and water temperature. Every factor is transparent. Tap any tile in the app to see the number, the reasoning, and the 24-hour trend.
Fishbrain is a social catch-log with a weather view bolted on; their moat is 14M+ logged catches. Submarius is a decision engine. We answer 'is today worth the drive?' with a single transparent verdict per activity. We don't compete on catch data; we compete on the verdict, on water-clarity forecasting (which Fishbrain doesn't do), and on keeping safety features permanently free.
Our primary focus is coastal saltwater, where wind, swell, tide, and marine-forecast signals drive fishing decisions. Inshore, offshore, and nearshore saltwater fishing all work well. Freshwater / bass fishing isn't our core use case; Fishbrain has a deeper catch-data moat there.
Yes. Current conditions, a 2 day forecast, basic Bite Score, and all safety features (shark alerts, buddy GPS, SOS) are permanently free, no signup required. Submarius Pro ($12.99 a month, $99 a year, or $149 once) adds the 8 day forecast, premium map overlays, offline maps, advanced bite score factor depth, and catch history export.
The input signals (tide, moon, pressure, temperature, solunar tables) are grounded in fisheries research. We weight them conservatively and explicitly. Solunar theory has mixed empirical support, so we include it as a moderate factor rather than a dominant one. No black-box 'AI' claims. The score is rule based today; a learned per region correction is planned as catch reports accumulate.