Ocean Water Clarity Map

Every spearfisherman and freediver asks the same question before a trip: what's the visibility going to be? There's no perfect answer, but satellite chlorophyll data gets you a real estimate before you've burned any fuel finding out the hard way.

How We Estimate Visibility from Chlorophyll

Chlorophyll concentration and water clarity are linked: more phytoplankton in the water means more light gets absorbed and scattered, which means you can't see as far. That relationship has been studied since Secchi disk measurements from the 1800s, and it lets us convert a chlorophyll reading into an estimated visibility in meters and feet. Roughly:

• 0.05 mg/m³ → around 36 meters (118 ft): deep blue oceanic water
• 0.1 mg/m³ → around 26 meters (85 ft): clear offshore water
• 0.3 mg/m³ → around 15 meters (49 ft): good visibility
• 0.5 mg/m³ → around 12 meters (39 ft): decent, slight haze
• 1.0 mg/m³ → around 9 meters (30 ft): green tinge, reduced clarity
• 3.0 mg/m³ → around 5 meters (16 ft): green, murky water

This number is a best-case ceiling, not a promise. It tells you the visibility you'd get if phytoplankton were the only thing affecting the water — in the real ocean, there's almost always something else in the mix too: sediment stirred up by waves, runoff after rain, or particles from nearby structure. Actual visibility is typically equal to or worse than the estimate, never better. Treat the number as an upper bound and the real conditions as whatever you find once you're in the water.

The range that matters most for spearfishing and freediving is roughly 0.2 to 2.0 mg/m³ — that's the band where the difference between a good day and a wasted trip actually lives, and where the estimate has historically tracked real-world visibility most closely. Readings well outside that range, in either direction, are still worth knowing but matter less to the go/no-go decision.

Reading the Map Before You Go

You don't need the formula to get value from the map — the color alone tells a story. Bluer water generally means better visibility; greener water means more phytoplankton and murkier conditions. Compare a few days of passes and you can see whether a bloom is building or dissipating, which tells you whether tomorrow is likely to be better or worse than today. For the full science behind the estimate — where it comes from, and where it stops working — see our article on estimating dive visibility from satellite data.

What Your Account Sees

Your account tier sets how current the clarity picture is. Guests see composites held back at least 48 hours — fine for a rough sense of conditions, not a same-day call. A free account removes that lag. A paid plan adds individual satellite passes and alerts for the region or regions your plan covers, useful if you're tracking a bloom day-to-day before committing to a trip.

Who This Is For

Built for spearfishermen, freedivers, and scuba divers deciding whether a trip is worth the drive — and for anyone who'd rather check a map than show up and find out.

The Florida Keys and Southern California are two of the most-checked regions for exactly this reason — both see chlorophyll swing widely enough, week to week, that a quick look before a trip is worth the habit.