See The Sea Bottom In 3D

Whether or not we truly do know more about the surface of the moon than the sea floor, those of us who spend our days hunting for remote fish-holding features on the bottom have no doubt that it’s possible. With new marine electronics hitting the market more often than some of us can get our boats out, keeping up with the newest trends and products can be a daunting task. For those primarily concerned with avoiding obstacles and keeping off the bottom, it can seem as though the latest and greatest is usually just more of a good thing we already have.

But every now and then a new technology comes along that is truly game-changing; that is, products that legitimately alter how we navigate, fish, and use our boats.

Shaded relief maps, or 3D charts, are one of those disrupters. While the newer iterations of inland and coastal charts have given us more contour lines and a better understanding of general underwater features, this new technology uses advanced hydrographic multi-beam surveys, LIDAR (light detection and ranging) imaging, and crowdsourced data (a formatted blend of user sonar logs and data points) to create detailed maps of the seafloor, using color shading to identify rocks, cliffs, wrecks, and objects present on the bottom. By combining these high- and low-resolution datasets, chart makers have developed comprehensive structure maps of the sea floor and lake beds, with regular updates providing more detail and new coverage areas as more data is obtained.

The implications are virtually endless for fishermen and divers. Traditionally, most types of offshore bottom fishing or diving trips began with a waypoint that marked some type of bottom structure, whether natural rock, reef, or something artificial like a wreck. Once we arrived at the point, our attention shifted to sonar, where we attempted to locate whatever feature we believed/knew to be on the bottom before marking with a buoy or using a trolling motor to maintain location. The introduction of detailed 3D mapping has completely changed this age-old way of fishing offshore. While traditional waypoints identified a specific location on the bottom, fishermen can now view the surrounding area, locating nearby features and “hidden” structures between the main ledges and reefs.

For those chasing pelagic species farther offshore, deep-water humps and canyons can now be located with pinpoint accuracy. Gone are the days of trolling for hours with eyes glued to the sonar, as detailed trip plans can now be made ahead, saving time and fuel, and hopefully, leading to fuller fishboxes.

The secret’s out

At first blush, it may seem as if these new charts will expose the “secret spots” that have been safeguarded by tight-lipped fishermen for generations, introducing hordes of new users to reefs already feeling the stress of increased fishing pressure. This was my initial reaction as well, but according to Erik Anderson, founder of CMOR Mapping, the new technology could, in fact, have the opposite effect.

Instead of a finite collection of waypoints shared by many people, the ability to see all the surrounding structure allows fishermen to “spread out,” alleviating concentrated fishing pressure on popular numbers and providing new grounds to explore, Anderson says. Anglers will always grumble about intruders on “their spot,” but in theory, new prime spots are revealed by this emerging technology.

The increased bottom awareness can also help preserve fragile reefs by allowing boaters to anchor in sandy patches, further lessening environmental use impacts. The bottom line: This new technology won’t increase the amount of people heading offshore to fish and dive but, rather, disperse them more widely.

The players

Depending on what chartplotting hardware you have on board, there are several marine electronics manufacturers currently offering shaded relief maps, with differing coverage areas and degrees of accuracy among products. Garmin introduced its relief shading layer in 2019 in response to customer demand for more information on the water, including easy-to-understand depth, bottom shape, and composition data. The company currently offers relief shading throughout nearly 50,000 lakes and many coastal areas throughout the world, with updates taking place at least every three months.

In the Garmin marine ecosystem, the relief shading feature can be downloaded via the companion ActiveCaptain mobile app and viewed on GPSMAP and Echomap chartplotters compatible with Garmin Navionics Vision+ and BlueChart g3 Vision mapping. The Navionics Boating app subscription provides a convenient way to view relief shading on mobile devices, and Navionics Platinum+ charts offer downloadable relief shading that can be viewed on compatible third-party chartplotters.

Navico’s C-MAP introduced in 2019 its own version of 3D mapping with its REVEAL charts, offering a shaded relief overlay for most coastal areas and select rivers and more than 15,000 U.S. lakes. Users can create their own custom shading, including setting a clear safety depth. C-MAP REVEAL and REVEAL X charts are currently available on most chartplotters in the Navico family (Lowrance, Simrad, B&G), as well as some other third-party devices.

In the private sphere, companies like CMOR Mapping and StrikeLines Charts have made it their sole mission to provide hardcore anglers with the most detailed relief charts available by using a fleet of private scanning vessels to map hundreds of thousands of square miles of the ocean floor. Founded in 2017, CMOR began offering relief charts to the public in response to demand for the highly detailed bathymetric data it had been collecting for government agencies. Its map chips are currently compatible with hardware manufacturers such as Simrad, Raymarine, Furuno, and Lowrance, and the SD cards can be purchased by region directly from the company’s website. The charts are updated once or twice a year, and card owners can send theirs in for updates as they become available.

Regardless of which chart makes the most sense for you, having access to this new data is guaranteed to change your fishing for the better, unlocking new areas and providing a better understanding of spots you have been fishing for decades. And if fishing isn’t your thing, watching the intricate undersea structures of the ocean bottom pass beneath you as you cruise along the surface is just plain cool.