GBOpen :Great Britain Map for Garmin Mapping devices
Technical notes
GMAP Version

Windows users :


If you do not have Garmin Basecamp then download and install from here.

If you are concerned about malware, use VirusTotal to scan the download link to check. http://www.virustotal.com

The map download will be a zip file, unzip it to see a .gmap folder.

Copy the .gmap folder (or a shortcut to it) to C:\ProgramData\Garmin\Maps\

Start Basecamp and under Maps you should see GBOpen (GBOpenPeak for the sample). In Basecamp you can view the map, load and edit tracks and routes. If the Maps item is not visible use View>Toolbars and check Map Products

[On some Windows systems, Basecamp will not find the file in ProgramData;
 an alternative place to copy is C:\Program Files (x86)\Garmin\Basecamp\Maps\]

The sample map is 4MB, the whole of Britain is about 1100MB. You will need this much free space on your Garmin device and I recommend that you load the map to a SD card rather than the main memory of the device.

To transfer to your Garmin device, connect it to your PC with a USB cable. Use Basecamp Maps>Install Maps and follow the instructions to load the map to your device.

If the map is visible in Basecamp but Basecamp says there are no unlocked maps, try copying a shortcut to the GMAP folder to

C:\Program Files (x86)\Garmin\MapInstall\Maps\


If this still fails, email me and I will give you a link to the IMG file that you can copy to the SD card on your device.

Mac users :

If you do not have Garmin Basecamp then download and install from the Mac App Store

The map download will be a zip file, unzip it to see the .gmap folder.

Open the .gmap file with Garmin Map Manager

Start Basecamp and under Maps you should see GBOpen (GBOpenPeak for the sample). In Basecamp you can view the map, load and edit tracks and routes.

The sample map is 4MB, the whole of Britain is about 1100MB. You will need this much free space on your Gamrin device and I recommend that you laod the map to a SD card rather than the main memory of the device.

To transfer to your Garmin device, connect it to your Mac with a USB cable. Use Maps>Install Maps and follow the instructions to load the map to your device.
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The map contains about 400 segments.

There are more detailed tutorials at GPSFileDepot

Note that many Garmin units have a maximum SD card size of 32GB - and the card must be formatted FAT32.

IMG Version

 Use this if you want to work with the map in applications such as QMAPSHACK or if you cannot use Basecamp to install the map. See the note above about SDcards.

Unzip the file. For QMAPSHACK use the file gmapsupp.img directly; for use with Garmin, on a blank SD card create a Garmin folder and copy the gmapsupp.img file into it. Do not try to install this on the device's own memory or to merge it with other maps on a SD card.

When the Garmin is attached to your desktop with the card installed the map will be visible in Basecamp.
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