Located in the sheltered harbour of Glengarriff in Bantry Bay, in Southwest Ireland, Ilnacullin (Garnish) is a small island of 15 hectares (37 acres) known to horticulturists and lovers of trees and shrubs all around the world as an island garden of great beauty.

The gardens of Ilnacullin owe their existence to the creative partnership, some seventy years ago, of Annan Bryce, then owner of the island and Harold Peto, architect and garden designer. The island was bequeathed to the Irish people in 1953, and was subsequently entrusted to the care of the Commissioners of Public Works.

Today, management of the island is in the hands of Dúchas, The Heritage Service of the Department of Arts, Heritage, Gaeltacht and the Islands.The island is named Garnish (the near island) on official Ordanance Survey Maps and is widely known by that name.

The alternative name Ilnacullin, or Illaunacullin (island of holly), also has a long history in the locality, and appears on at least one early map; it may in fact be the older name for the island.

The alternative name Ilnacullin, or Illaunacullin (island of holly), also has a long history in the locality, and appears on at least one early map; it may in fact be the older name for the island. As there is another island garden called Garnish not far away in County Kerry, there is much to be said for using the distinctive name Ilnacullin for the island garden at Glengarriff, County Cork, and this has been the practice for some years now.