Larne Lough, historically Lough Larne (from Irish Loch Latharna),^[2] is a sea loch or inlet in County Antrim, Northern Ireland. It lies between the Islandmagee peninsula and the mainland. At its mouth is the town of Larne. It is designated as an area of special scientific interest, a special protection area, and a Ramsar site to protect the wetland environment, particularly due to the presence of certain bird species and shellfish.

The lough takes its name from the small medieval territory of Latharna meaning "descendants of Lathair". The older name for the lough was Loch Ollarbha or Inbhear nOllarbha, from Ollarbha, the ancient name of the Larne Water.

Chaine Memorial Tower lighthouse is on the west side of the entrance to Larne Lough.

In 1929, a "Coastal Survey" of the algae of the north-east of Ireland was begun when a few members of the Botanical Society in The Queen's University of Belfast investigated and mapped the distribution of the seaweeds. Among the algae recorded was Ascophyllum nodosum var. minor Turn.^[3] The northern end was also surveyed.^[4]

The Belfast-Larne railway line brings the line alongside the shore line from Larne Harbour, Larne Town, Glynn, Magheramorne, and Ballycarry, over the section of land linking Islandmagee to Whitehead railway station then running alongside Belfast Lough via Carrickfergus and Belfast Central to Belfast Great Victoria Street railway station.

• List of loughs in Ireland
• List of Ramsar sites in Northern Ireland