The Discovery Series are designed for tourist and leisure activities. Each one covers an area of 40km x 30km at the scale of 1:50,000. There are 93 sheets in the series. 75 are produced by Ordnance Survey Ireland and 18 by Ordnance Survey Northern Ireland. The maps produced by Ordnance Survey Northern Ireland are called the Discoverer Series. Discovery Sheet No. 31 covers part of County Mayo.