UK citizens do not require a passport or visa to enter Ireland, but most carriers by air or sea now require some form of identification with photograph (usually either a passport or driving licence with photo). Visitors are advised to check what form of ID is required with the individual airline, ferry company, tour operator or travel agent before travelling. 

Non UK nationals must have a valid passport or national identity card as appropriate.

Citizens living within the EU and most other Western countries including Australia, Canada, New Zealand and South Africa do not require visas.

All other countries should contact their local Irish Embassy/Consulate prior to travelling to the Republic of Ireland, and visitors to Northern Ireland should contact their local British Embassy/High Commission or Consular Office. 

Embassies & Visa Contacts

Further information for the Republic of Ireland, including a full list of Irish Embassies, is available from: 
The Department of Foreign Affairs (Tel: + 353 1 478 0822)
or
The Passport and Visa Office
Irish Embassy, Montpellier House, 106 Brompton Rd, London SW31JJ 
Tel: ++ 44 207 225 7700 

Further information for Northern Ireland is available from your local British Embassy or Consulate, for details please contact:
The Foreign and Commonwealth Office (Tel: + 207 008 1500)

For an extension to your stay in Northern Ireland contact:
The Undersecretary of State (Tel: 0870 606 7766)