updateRefreshed June 23, 2026

Hard Bottom Structure Maps

See confirmed NOAA seabed evidence and Fish Fathom structure markers produced from NOAA public data in one scan-friendly map layer.

Fish Fathom Hard Bottom layer showing NOAA seabed evidence along the U.S. coast

What The Upgrade Adds

The Hard Bottom layer now combines confirmed NOAA NOS seabed points with additional Fish Fathom structure markers produced from NOAA public data. Instead of generic dots, the map uses structure-aware symbols and color families that make hard bottom, ledges, reef-like structure, potholes, and other seafloor texture easier to scan.

Confirmed NOAA points use stronger symbols. Additional NOAA-public-data markers use lighter symbols so they read as scouting context. Both remain controlled by the standard Hard Bottom layer control and opacity setting.

Coverage Examples

Fish Fathom app showing NOAA public data hard-bottom structure markers in the Gulf of Mexico
Gulf structure overlay NOAA-public-data structure markers group at broad views and reveal spot types as you zoom in.
BlueTopo relief and contour detail near Tampa Bay
Tampa Bay detail High-definition contours help reveal ledges, relief changes, and hard-bottom texture.
East Coast BlueTopo coverage example
East Coast source coverage Structure coverage follows supported NOAA public source regions.
West Coast BlueTopo coverage example
West Coast source coverage Expanded processing is built to work across supported BlueTopo areas, not only one Gulf sample.
Alaska BlueTopo coverage example
Alaska source coverage Broad coastal source coverage helps keep hard-bottom exploration regional, not local-only.

Why It Matters Offshore

verified

Confirmed Evidence

NOAA seabed points remain visible as stronger confirmed markers with survey-backed bottom context.

travel_explore

New Structure Areas

NOAA-public-data markers highlight structure you may not already have saved as waypoints.

layers

One Layer

The existing Hard Bottom layer now carries confirmed NOAA points and additional NOAA-public-data structure markers.

palette

Fast Color Read

Yellow, orange-red, blue-cyan, violet, and gray categories make structure families easier to scan.

speed

Viewport Rendering

Fish Fathom queries and renders the current viewport instead of drawing every marker at once.

route

Trip Planning Context

Use structure markers with routes, waypoints, HD bathymetry, and your existing fishing history.

Legend: Public Structure Categories

Low Natural

Color: Yellow-gold

Includes: Hard bottom, swiss-cheese limestone, and low-profile hard-bottom texture.

How to use: Screen broad zones where bottom texture changes from sand or mud into firmer habitat.

Big Natural

Color: Orange-red

Includes: Ledges, boulders, rock piles, outcroppings, escarpments, pinnacles.

How to use: Prioritize sharper bottom changes and edges for closer chart review and on-water verification.

Spring, Sinkhole, Pothole

Color: Blue-cyan

Includes: Springs, sinkholes, potholes, and circular depressions.

How to use: Look for unusual bottom changes and nearby bait or current breaks.

Artificial Structure

Color: Violet

Includes: Reefs, wrecks, pipelines, and confirmed artificial structure.

How to use: Artificial labels use corroborating public source data.

Unknown Structure

Color: Muted gray

Includes: Structure-like signatures that do not fit a higher-confidence category.

How to use: Treat as a scouting hint and compare against sonar, current, and local knowledge.

Confirmed vs NOAA Public Data

NOAA: Solid, stronger outline means confirmed seabed evidence.

NOAA public data: Lighter outline means additional structure context produced from NOAA public data.

Best practice: Verify every spot on the water before relying on it.

Expanded Coverage

Currently available: Hard Bottom includes NOAA NOS seabed points where those records exist and additional structure markers produced from NOAA public data across supported coverage areas.

  • Confirmed source: NOAA NOS seabed type points with hard-bottom classes highlighted.
  • Additional source: Fish Fathom structure markers produced from NOAA public data.
  • Rendering: Broad views group dense areas; closer views reveal individual structure markers.
  • Scope: Wrecks, pipelines, reefs, and artificial categories use corroborating public source data.

Hard-bottom data is one planning signal. Combine it with HD bathymetry, navigation charts, weather, vessel activity, your waypoints, and your own sonar before committing to a spot.

How to Use It

1

Turn On Hard Bottom

Open Layers and enable Hard Bottom. The upgraded structure overlay is now the default behavior.

2

Read the Source

Solid NOAA markers mean confirmed evidence; lighter structure markers are produced from NOAA public data.

3

Compare Layers

Overlay HD bathymetry, contours, routes, and existing waypoints to decide what deserves a scouting pass.

4

Verify On The Water

Use the map to narrow the search, then confirm bottom, relief, and life with your electronics.

Find More Structure Before You Run

Use Fish Fathom to scan confirmed hard-bottom evidence and NOAA-public-data structure markers across supported coastal coverage.

Download for iOS Download for Android