Other cache owners have set challenges based upon squares of Ordnance Survey maps, here are some you may be interested in, some of which are also shown on the UK Map page
- GC41VR6 Geosquare SP - Five Across Challenge by Superted
- GC4P54M Welsh Geosquare Challenge by Superted and PetersfieldPoodlePosse
- GC5FPJ0 South Gloucestershire Challenge (resurrected) by Andy&girlsUSA