Ynys Gaint is a small island in the Menai Strait connected to the town of Menai Bridge on Anglesey by a causeway (which still exists today) and also a concrete bridge erected by Sir Guy Fison (a previous owner of the island) in the 1930s.
Ynys Gaint lies close to the Anglesey shore at OS reference SH561725, between Ynys Faelog and Ynys Castell. Between 1942 and 1944 the island housed a Royal Air Force air-sea rescue unit, with several high speed launches, and a small part of the island is still occupied by the MOD with an Army Cadet hut and also a building formerly used by the Naval Reserves (now Volunteers). There are also two privately owned residential properties on Ynys Gaint. One of these had a portion of its garden designed by the late Sir Clough Williams-Ellis, of Portmeirion fame.