What each layer shows, where it comes from, how it affects the fish, and what to watch for. Most layers follow the day on the time bar and the area you are looking at. Anything marked live-site only needs the deployed site, not a saved copy, to pull data.

Sea surface temperature

For fish: the number one filter. Every pelagic sits in a temperature band, and the sharp breaks between warm and cool water stack bait and hold tuna, marlin and mahi. Start every read here.

High-res & fronts. The default. A sharp, roughly 2 km satellite view that shows the real breaks and fingers the fleet looks for. Clouds show up as gaps.

Geo-Polar Blended. NOAA's all-sensor blend — VIIRS, AVHRR, GOES, Meteosat and Himawari merged into one daily, gap-free 5 km map, bias-corrected between sensors. For fish: the cleanest full-coverage read when clouds wreck the high-res view. It is smoother and lower-res than the fronts layer, so lean on it for the big picture and switch to High-res for the hard edges.

GOES-19. A live view that refreshes every couple of hours, for the freshest look at the water.

Forecast SST. A model that runs into the future, so you can drag the time bar past today to see where the water is headed.

Temp at depth. The water below the surface, where the break and the thermocline set up for tuna and swords.

Mixed layer depth. How deep the warm surface layer mixes before it hits the thermocline, from the Copernicus model. For fish: shallow mixing means tuna are pinned near the surface and easy to reach, while a deep mixed layer spreads them out and pushes the bite down.

GOES-19 24 h composite. The last 24 hourly GOES-19 passes stacked into one image, keeping the freshest cloud-free pixel at each spot. For fish: it fills the holes any single GOES snapshot leaves, without smearing a moving break across days like a weekly composite would. Built live in your browser for the current view.

SST break / fronts. Highlights the temperature edge itself. The brighter it is, the faster the temperature is changing over a short distance.

SST contours. The same edges drawn as labeled temperature lines. Tip: pinch the temperature scale in the bottom dock tight around the break, roughly 60 to 72 degrees, to make the edge pop.

Weather

For fish: mostly indirect. Wind and sea state decide whether you can get out and how bait pushes around, and fog is a safety and run-planning call, but none of these tell you where the fish are holding.

Wind. A colored field plus arrows for wind direction, from the coast out past Bermuda, for the next three days.

Waves. Swell height and direction over the same range, for planning the ride out.

Fog & visibility. Paints only where the visibility actually drops.

Radar. Live weather radar. It thins out far offshore. The opacity slider in the bottom dock dims the colored wash while the arrows stay solid.

Currents & tides

For fish: this is where edges are made. Currents set where fronts and eddies form and where bait concentrates, and warm-core ring edges are prime. Tides matter inshore but barely move the needle at the canyons.

Surface currents. The general set and drift and the big eddy circulation, not the fine inshore stuff.

Fronts & eddy edges. Lights up where currents are straining water together, which is where bait stacks.

Sea surface height. The humps of warm water. Highs are warm-core eddies; swirls are Gulf Stream meanders pushing blue water toward the canyons.

Sea level anomaly. Altimetry showing how far the sea surface sits above or below normal. For fish: the cleanest eddy read there is. A positive bump is a warm-core clockwise ring of blue water, a negative dip is a cold-core ring; work their edges.

GoMOFS. A regional current model covering the Gulf of Maine and Georges.

STOFS. A broader shelf current model that reaches the canyons.

Shaded water level. An inshore water-level tool tied to tide stations.

Tidal-current arrows. Inshore tidal set, tied to tide stations. Barely a factor out at the canyons.

Salinity

For fish: a water-mass cue. It marks the boundary between fresher shelf water and saltier Gulf Stream water, which often lines up with the temperature break. Mahi in particular avoid the fresher water, leaving anything below about 34.25.

Salinity. A model of how salty the water is, at a depth you pick. The scale is stretched so the boundary stands out. Turning it on hides the other color layers, but the break line still draws on top.

Chlorophyll & true color

For fish: color is a hard boundary. Work the clean blue side of the green-to-blue edge; that color break is a line many pelagics patrol, and the greener, more productive water feeds the bait below them.

Chlorophyll. Shows how green or blue the water is. Fish the clean blue side of the color edge.

Chlorophyll gap-filled. Cloud-free but a little coarser, so it is the one to trust on cloudy days.

Chlorophyll edge / color front. A derived layer that lights up the sharp green-to-blue color break, the same idea as the SST break but for water color. For fish: that color line is a primary edge pelagics patrol, best when it stacks right on the temperature break.

True color. The actual look of the water from space, one pass a day, so clouds show as gaps. Pair it with temperature to confirm a break is real, and step the day back for a cleaner shot.

Sargassum / weed (AFAI). A floating-algae index from NOAA AOML that flags weed lines and mats. For fish: weed is structure for mahi, wahoo and white marlin. Coverage is strongest in the Gulf and Southeast; up here it mostly shows weed riding the Stream edge, so treat it as a bonus, not a primary.

Map & markers

For fish: structure concentrates them. Canyons, ledges and the 100-fathom line turn a moving edge into a reliable spot when the warm water sits right on the bottom.

Bathy relief. A shaded picture of the seafloor. Turn the temperature layer off to read the bottom.

Nautical chart. The NOAA chart. Drop its opacity to read depths over the break. It is not for navigation.

Spot pins. A solid diamond is a charted feature or buoy; a hollow amber diamond is an approximate community mark, so confirm it on your plotter.

Vessels (AIS)

For fish: a weak hint at best. A cluster of boats can flag activity, but coverage stops well short of the canyons and many sportboats run with AIS off.

AIS. Live boat traffic relayed through this site. Shore-based coverage reaches about 50 NM out, so it shows the shelf and the ride out but not the canyons, which need paid satellite tracking.

GPS & tracks

For fish: nothing directly. This is navigation and logging, useful for getting back to a mark, not for finding one.

Recording. Works only while this page is open and the screen is awake. It is not a background app.

Offline behavior. GPS works with no cell signal, but the map and temperature tiles need data to load, so they will be blank offshore unless you loaded them first. Your tracks and waypoints are saved on this device.

Data sources

Temperature from NOAA and NASA satellites. Chlorophyll from NOAA and NASA. Salinity and currents from Copernicus Marine. Radar from the National Weather Service. Seafloor from Esri and GEBCO.

Why the canyon reports look thin

The reports here are the dated public ones from the latest scan. Striper intel is well covered, but bluefin and canyon reports are sparse and early, because the live tuna talk lives in closed groups, members-only forums, and texts that a web search cannot reach. Paste screenshots or texts from your own groups and an AI chat can drop them on the map as fresh pins.