The Parish of North Mundham contains the villages of North Mundham, South Mundham and Runcton as well as the hamlets of Bowley and Fisher and stretches from the A27 Chichester bypass, which since its completion in 1959 has formed the northern boundary, about 8 kilometres southwards to Pagham Harbour which forms its southern boundary. It is never wider than 3 kilometres from East to West.

The Parish consists of mostly high grade agricultural land, flat and all less than 10 metres above sea level.  In common with the rest of the Sussex coastal plain the Parish enjoys a very high winter light factor and is thus highly suitable to the glasshouse industry.  Traditionally most of the land was used for dairy farming and sheep and there were quite a number of glasshouses enterprises, but towards the end of the 20th Century changes in the nature of farming and the decline in the glasshouse industry has resulted in significant changes.  The land in now mostly arable, much down to lettuce grown in the open air.  Only the larger glasshouse businesses survive grouped on or around the Runcton Horticultural Area (H.D.A) which was designated in 1996 on the old Merston Airfield to the North of the Walnut Tree Pub.  Much of the southern part of the Parish comprises of water meadows and is prone to flooding but the northern part is drained by the Pagham and Bremere Rifes and their associated ditches.  The Chichester Flood relief scheme uses the rifes and is intended to divert the occasional flood waters of the River Lavant down the eastern boundary of the Parish through sluice gates in the Pagham Harbour wall to the sea.

In the north western corner of the Parish there was extensive gravel extraction between 1920 and 1965 resulting in a number of lakes which are now a significant geographical feature and used for angling and water sports.

About 1.3 kilometres south from its northern boundary, the Parish is traversed in an east/west direction by the now defunct Chichester to Arundel Canal and also by the Lower Bognor/Lagness Road (B2166) which links both Bognor and Pagham with Chichester via Vinnetrow Road or the Selsey Road (B2145).  Two country lanes run southwards through the Parish from the B2166.  In North Mundham, Church Road leads to St Stephen’s Church (partly 13th Century) and then, as Fisher Lane onto Fisher.  In Runcton, Mill Lane leads south to the Runcton Conservation Area which contains a number of houses of architectural interest situated around Runcton Mill and then as Runcton Lane onwards to Bowley.  South Mundham and Honer can be reached by either of these lanes but further south both peter out into farm tracks and there is no vehicular access either to Pagham or the Sea.  A network of ancient footpaths and bridleways criss-cross the Parish and are well worth exploring particularly in the beautiful area between South Mundham and Pagham.  A significant part of the Pagham Harbour Local Nature Reserve lies within the Parish.

The Millennium Map of the Parish can be seen in the Village Hall which is next door to North Mundham Primary School.  The inscription which forms the border to this map reads:

‘This map shows the Parish at the start of the 21st century.  Most parishioners hope that its rural charm and peaceful beauty will be retained for future generations to enjoy.’