Exploring the Depths With Bathymetric Data

Global Mapper® has made a name for itself with support for over 380 file formats, powerful lidar classification tools, and a reputation for top-tier technical support. What’s perhaps less widely recognized is its robust tools for generating, analyzing, and visualizing bathymetric data.

Bathymetry is the study of underwater terrain such as ocean floors, lake bottoms, and riverbeds. As over 70% of Earth’s surface is hidden beneath water, bathymetric analysis plays a crucial role in mapping and understanding the environment. Let’s explore how Global Mapper’s analysis and visualization features can streamline and enhance bathymetric workflows across a range of industries.

What are Common Bathymetric Data Formats?

Mapping the seafloor and other underwater terrain can be done in many ways—from ship-mounted sonar, to AUVs, and even satellite multi-spectral imagery. High-resolution bathymetric surveys often rely on multibeam echosounders to capture detailed depth measurements. With its broad file format support, Global Mapper handles data from all of these marine navigation systems and subsurface remote sensing with ease. Below are some of the most commonly used bathymetric formats.

Marine Navigation and Nautical Charts 

• S-57 / S-63 / S-101 – International hydrographic chart standards 
• NOS/GEO (National Ocean Service Georeferenced Bathymetry Format) –  Stores gridded data from NOAA surveys with georeferencing  
• NV Digital (NV Verlang) – Electronic nautical raster chart 
• PCX (PiCture eXchange) – Raster image storage format that can be used in legacy sonar or charting

Sonar & Sounding Data 

• Lowrance Sonar – Stores depth soundings, sonar imagery, and GPS information collected by Lowrance fishfinders and chartplotters
• XTF (eXtended Triton Format) – Widely used for sidescan and multibeam sonar 
• GSF (Generic Sensor Format) – Stores raw sonar and navigation data, often used as an interchange format
• HTF (Hydrographic Transfer Format) – Stores processed hydrographic survey data including depth soundings and positions 
• ALL / WCD – Kongsberg multibeam echosounder formats
• HSX (Hypack Survey Export) – Hypack survey format of raw single-beam or multibeam sonar pings with GPS time and position

Gridded/Raster Bathymetric Data

• BAG (Bathymetric Attributed Grid) – NOAA/CHS standard for storing gridded bathymetry with uncertainty values
• DBDBV (Digital Bathymetric DataBase) – Common global bathymetric database format for storing grids at variable resolutions
• NITF (National Imagery Transmission Format) – Standardized raster imagery container 
• NetCDF / CF-compliant – Used for oceanographic grids, including bathymetry
• GeoTIFF – Common for storing processed bathymetric grids with georeferencing
• ASCII grid – Gridded bathymetry as plain text for easy import 

Point Cloud & 3D Surface

• LAS / LAZ (compressed LAS) – Standard point cloud format
• XYZ / CSV – Simple tabular format with X, Y, Z depth points
• SD / DXF / DWG – CAD style formats for 3D models or contours

Visualize the Seafloor

Global Mapper offers a wide variety of tools for visualizing and analyzing bathymetric data. Users can choose from a list of elevation shaders—such as slope and Relative Elevation Model (REM)—or design custom shaders to highlight depth variations and reveal subtle submarine features. These shading options make it easier to interpret slope steepness, orientation, and other aspects of the underwater terrain.

The 3D Viewer transforms bathymetric datasets into an immersive environment, allowing users to explore the seafloor from any angle. Walkthrough and flythrough recordings make it simple to share these dynamic perspectives. Within the 3D view, users can also run further analyses—such as simulating water level changes.

How to Create a Bathymetric Profile 

One of the most effective ways to interpret the seafloor is by generating a bathymetric profile—a cross-sectional “slice” through the terrain that reveals how elevation changes. With the Path Profile tool users can either draw a path or select an existing line feature to instantly create a bathymetric profile. Furthermore, a large scope of the terrain can be acquired by creating a series of sequential cross-profiles. For broader scope of the terrain, a series of sequential cross-profiles can be generated, helping identify patterns across the landscape.

Can Bathymetric Data Be Combined With Other GIS Data? 

As previously mentioned, there is an expanse of possible data to analyze during a bathymetric project. Global Mapper makes it easy to merge data from different surveys or sensors—simply load the datasets, arrange the layers, and it’s ready to go. 

When working with data in different projections, GeoCalc® Projection Mode in Global Mapper automatically aligns coordinate systems and datums, with batch processing available for large datasets. Global Mapper can merge layers into a single surface and enable side-by-side comparison of multiple surfaces. Additional options—such as cropping, aligning, feathering, and layer comparison—help ensure smooth integration between diverse datasets.

This approach has been invaluable for Australian scientist Dr. Robin Beaman and his ocean mapping team at James Cook University. They have combined hundreds of bathymetric surveys into a seamless bathytopo model of the Australian coastline. 

Create Bathymetric Point Clouds From Sonar

Sonar and other sensor data can be transformed into manageable, analysis-ready point clouds in Global Mapper by exporting them to the LAS format. Once in this format, the full suite of point cloud tools becomes available, including automatic classification to identify the seafloor, distinguish other subsurface structures, and remove unwanted noise. 

From there, the Create Elevation Grid tool can quickly generate a detailed seafloor surface. This workflow has been used for applications ranging from shipwreck detection and modeling to identifying subtle underwater features that might otherwise go unnoticed.

Analyze the Seafloor 

Once bathymetric data is combined and visualized, the next step is analysis. Global Mapper offers a wide range of tools to transform a terrain model into actionable insights—helping users address real-world challenges in marine science, engineering, and environmental management.

Subsurface Contouring

Contours are not simply for hiking trail maps; Global Mapper’s Generate Contours tool can generate precise contours for the underwater terrain or shorelines from loaded gridded data. The resulting line features can be edited, stylized, and combined with other datasets to create custom bathymetric charts. Alternatively, enclosed contours can be automatically converted into Iso-height areas that show the water extent at different depths or sea levels.

Measurement and Volume Calculation

Global Mapper can be used for precise quantitative analysis of bathymetric data. In the standard 2D Map View, Path Profile window, or 3D Viewer, the Measure Tool provides quick calculations of distances and areas.

For water volume analysis, the Calculate Cut and Fill Volume tool offers several approaches: defining a fixed height or plane, calculating volumes across a range of water levels, or comparing bathymetric data to a reference surface grid. These methods make it easy to estimate changes in sediment accumulation, plan underwater construction projects, determine the volume of shipwreck debris, or evaluate dredging requirements.

Flood Modeling

By integrating bathymetric data with terrestrial terrain models, tools like Generate Watershed and Water Level Rise can reveal flood extents, model flow accumulation, and support a wide range of hydrographic studies.

With Global Mapper’s terrain editing and creation capabilities, users can produce hydro-enforced DEMs or other customized surface models that accurately represent water flow. These enhanced datasets can be analyzed directly in Global Mapper or exported to numerous formats for use in other applications.

Beyond Depth: Mapping Temperature, Salinity, and More

Bathymetric analysis often benefits from integrating other gridded datasets—such as surface temperature, salinity, gravimetric measurements, and more. These complementary layers can be visualized alongside depth data, rendered in 3D, and contoured to reveal patterns and relationships within lakes, oceans, and other water bodies. By combining these variables, analysts gain a richer understanding of the physical and environmental dynamics at play beneath the surface.

From mapping the contours of the seafloor to merging multi-sensor datasets, bathymetric analysis in Global Mapper offers an unparalleled view of the world beneath the water’s surface. The ability to visualize, analyze, and share this information empowers researchers, engineers, and planners to better understand marine and freshwater environments—ultimately supporting a wide scope of industries including navigation, habitat conservation, and sustainable development.

Explore these bathymetric analysis tools—and countless others—firsthand with a free 14-day trial of Global Mapper Pro.