Contents: Ordnance Survey Maps (UK)

Key facts
What are OS maps?
Mobile download code
Great detail and legal rights of way
OS maps don’t mark all paths
OS maps can’t show fine detail

Key facts

Website	https://shop.ordnancesurvey.co.uk/
Map type	OS mapping. Raster. ie Converted paper maps.
Which devices?	Readily available for a variety of phone apps. They are available for some dedicated GNSS devices.
File type and approx size for UK	3GB for the standard definition 1:50k Landranger maps. 12GB for the standard definition 1:25k Explorer maps.
Cost	Approx £30pcm for subscription options. Approx £150 for UK at 1:25k & 1:50k maps from Memory Map (Perpetual license) & £300+ for Garmins.
Areas covered	Great Britain
Contours, crags, ground, property boundaries.	All are well detailed. 5m vertical interval contours on gentle terrain
Paths and tracks	Great detail. However not all footpaths are marked and paths aren’t colour-coded according to difficulty.
Public Rights of Way and access land	PRoWs and access land are all clearly highlighted.
Map styling	None. The maps behave like photos of the paper versions.

What are OS maps?

OS maps are the official government-funded maps for the UK, produced by the Ordnance Survey, which is the body responsible for providing detailed mapping. If you were only ever going to use one type of mapping for adventures across the UK, the OS mapping is what you’d choose. If a navigation app offers OS topo maps, it will be these.

The OS produces orange Explorer (1:25,000 scale) and pink Landranger (1:50,000 scale) paper maps designed for adventuring in the outdoors.

Mobile download code

Notice the ‘Mobile download’ logo on the covers. A scratch-off panel inside the cover reveals a code. Entering that into the OS Maps phone app enables a free download of the digital version. This is unique to the OS. You only need a free OS Maps account for this to work. The codes are saved with your account. Then if your phone breaks you can download the maps again onto a new phone. You only need to subscribe to the app if you want to download mapping that you don’t have mobile download codes for. Subscription mapping will disappear if you stop subscribing, mobile download code mapping is permanent.

Great detail and legal rights of way

These maps have a well-deserved reputation for being high quality and provide accurate, consistent coverage everywhere. The information is presented in a way that’s suitable for outdoor use and there will be few outdoor fans in the UK who haven’t used them.

Both the Explorer and Landranger maps show the legal Public Rights of Way.
WARNING: These ‘PRoWs’ are often just markings on a map and not represented by anything useful on the ground. They have encouraged hikers into trouble, as some PRoWs go through dangerous terrain where there is no path. Learn about why that is and how to spot a potentially dangerous PRoW here.

The 1:25k maps will be a popular choice for many UK hikers. The scale is usually ideal for a day out and the maps show details that are absent from the 1:50k maps. The following features are particularly useful…

• Extra paths are marked.
• Open access land is marked.
• Boundaries like fences and walls are marked. Useful for ‘handrailing’ in bad weather.

See the extra paths at the top of the square on the 1:25k map. Extra woodland and streams are seen and the access land is marked with a salmon coloured boundary and a faint yellow wash. You can’t miss the extra field boundaries on the farmland.

Contour and crag information is superb. In hilly areas the vertical interval between contours is generally 10m but this reduces to just 5m for more gentle countryside.

OS maps don’t mark all paths

Good though OS maps are, there are many well-trodden paths over wilder ground that are not mapped. This is particularly noticeable in the highlands of Scotland where even in hotspots like Glencoe and Torridon, many mountain thoroughfares remain unmapped. Lots of those missing paths are shown on OSM-based maps. If you visit the Scottish wilds an OSM-based map on your phone is very handy.

See the following map comparison. The two maps are of the Stob Coire Nan Lochan area. This is a fine peak on the south side of the popular hiking and climbing area, Glencoe. The top map is a WayMap made by the WalkLakes.co.uk crew. This uses OS contour and crag data, but crucially, the marked paths are from OpenStreetMap. See how many there are. The lower map is the government-funded OS 1:25k Explorer map. It only has a couple of paths up the valley floors. This is not unusual.

If you need any more convincing that having an OSM map on your phone is a good idea, then visit walklakes.co.uk and register (free). That will give you access to OS mapping and the WayMaps which contain OSM paths. Now take a wander round the high mountains of Scotland and anywhere else you fancy. You can compare the OS maps with the WayMaps via the map layers button in the top left-hand corner.

OSM-based maps also offer extra paths in the well-mapped Lake District. I doubt the green PRoW across the OS map is a real path on the ground.

The OSM mapping can only get better as more people continue to upload GPS data to OpenStreetMap. Keep at least one with you. The extra path options alone are worth having.

On an early autumn wild camping trip around the Lake District, my wild-swimming friend wanted a dip in a very chilly Sprinkling Tarn. It was a beautiful day for it. Afterwards we would be heading over Scafell Pike with our heavy rucsacs on.

The most direct line from the tarn to Scafell Pike would be straight over an imposing Great End. The Great End cliffs look intimidatingly steep from Sprinkling Tarn, with no paths up shown on the OS map (just a boundary on the ridge crest). 

My OSM-based maps all showed a good path running up the spine of Great End and we could see a grassy ramp that angled up to meet it. Ideal. It saved us a kilometre detour and provided a quieter route up.

OS maps can’t show fine detail

Not a flaw but a disadvantage of 1:25,000 scale OS maps. The scale is too small to capture fine detail. The OSM-based maps have no practical limit to the fine detail that may be mapped and it shows.

This is immediately obvious in towns where OS maps are of little use. Some OSM-based vector maps will show the exact position of cashpoints, phone boxes, picnic tables, post boxes, recycling points, park benches, defibrillators, etc. It’s a long list. Also well marked, and usually named, will be shops, B&Bs, pubs, banks, pharmacies, restaurants, hotels and supermarkets etc. This information is great if you’re heading into an unfamiliar town. All stored offline on a map which requires no internet connection.  

This fine detail is not limited to built-up areas. Wandering around the summit of Ben Nevis requires care in winter and bad visibility. The usual path down to Glen Nevis requires a curved line around the head of Gardyloo Gully, which is likely to be dangerously corniced. The better OSM-based maps detail the individual cairns marking a safe line. The ‘green comb’ represents the cliff edges in the OsmAnd map at the top.

Climbers might also appreciate the extra detail offered by an OSM map when looking for a particular rocky buttress. Rock features just metres apart may be named on the map. OS mapping can’t compete. If your local rock face isn’t yet marked up, you can get online and fix that at OpenStreetMap.com.