The town of Shoreham-by-Sea is built in a low level area situated between the South Downs and The English Channel. The town is bordered by the River Adur to the West and the town of Southwick to the East.

The town is built on a south facing slope from a height of 30m above sea level down to to 7.7m above sea level. Above 30m housing and development have been stopped and this gives way to farmland and the hills of The South Downs. Due to the River Adur to the west of the town and Shoreham (Brighton & Hove) Airport , there is no development of housing to the east of the Steyning Road.

The highest point around Shoreham-by-Sea is Erringham Hill with a height of 104m, although the better view of the town and Shoreham (Brighton & Hove) Airport is from The Mill Hill Nature Reserve at a height of 67m.

The highest point of The South Downs in the Shoreham-by-Sea area is Truleigh Hill, which is crossed by the South Downs Way, at a height of 216m. Truleigh Hill is accessable from Shoreham via a direct road along Mill Hill. This road, however is not passable, without a 4x4 after reaching the Youth Hostel.