The North Slob is an area of mud-flats at the estuary of the River Slaney at Wexford Harbour, Ireland. The North Slob is an area of 10 km2 that was reclaimed in the mid-19th century by the building of a sea wall. It is the lowest geographical point on the island of Ireland.

Wexford Harbour in County Wexford, Ireland is the natural harbour at the mouth of the River Slaney. In earlier times, the area occupied by the harbour was considerably larger than it is today, up to ten miles (16 km) wide at its widest point, with large mud flats on both sides. These were known as the North Slob and the South Slob from the Irish word slab, meaning mud. It contained several islands, among which the large island of Beggerin was known to be a safe refuge for early Christian settlements.