Anglesey Sqn Search and Rescue Helicopters, both units providing employment for about 500 civilians. RAF Valley is now the headquarters of 22 Sqn Search and Rescue. There is a wide range of smaller industries, mostly located in industrial and business parks, especially at Llangefni and Gaerwen. These include an abattoir and fine chemical manufacturing, as well as factories for timber production, aluminium smelting, fish farming and food processing. The island is also on one of the major routes from Britain to Ireland, via ferries from Holyhead, off the west of Anglesey on Holy Island, serving Dún Laoghaire and Dublin Port. Much
Port of Holyhead trade war with the newly established Republic of Ireland had an adverse effect on the level of use of the port, which caused widespread unemployment in the town of Holyhead. During the Second World War, however, the Royal Dutch Navy began using the port as a base. In June 1939, the Royal Navy submarine "HMS Thetis" sank during sea trials in Liverpool Bay and it was subsequently brought to the harbour at Holyhead after being beached at Traeth Bychan. It remained at Holyhead in dry dock while the contents were removed; fourteen of the 99 victims were buried locally. A