Updated Dec 2018, May 2019 and Nov 2022

Since the death of Professor Charles Read, his website at Leeds University has disappeared, however parts of it, but not the .gpx/.gpi files are available at archive.org, as well as at https://solocavediver.com/

(As an aside, I note that he has an Erdős number of 4)

OsmAnd is a free map app for Android, available from the Google Play Store: OsmAnd — Maps & GPS Offline.

Download and install, then add a couple of maps: "UK England Yorkshire" and "UK England NW". You might want to add contour lines, too. You can download a few maps free of charge and it's not a lot for a yearly subscription for unlimited downloads. The maps are stored on your phone, so good for places where connectivity is poor or expensive (I've used it in the Canary Islands).

To overlay the co-ordinates of caves:

* Use the Chrome browser
* visit https://cavemaps.org/data/
* accept the "connection not secure" warning
* long click on each of the three links to an nc .gpx file.
* save to the Downloads directory

* In OsmAnd, tap on the three bars at the bottom left to open the menu
* "My places", "My Tracks", "Import"
* Tap on the icon for a file, it changes to a tick, then "Open"
* for subsequent imports, click on the "+" at the bottom left.

* Finally, on the "My tracks" page, tap on the three dots to the right of a file and "show on map".