The island of Ireland is made up of the Republic of Ireland (a sovereign state of its own) and Northern Ireland, which is a dominion of the United Kingdom. As such separate visa requirements are necessary when visiting each; the details of which are explained below.

Entry Visas for the Republic of Ireland:
Persons who are holders of a British Hong Kong Passport who have a right of abode in Great Britain do not require entry visas. 

Persons who are holders of a British Hong Kong Passport who have a right of abode in Hong Kong only do not require entry visas but they are subject to full foreign national controls in respect of registration, permission to remain, work permits etc. 

Persons who are holders of a Hong Kong Certificate of Identity require an entry visa for the State. Such persons should refer to the Consulate of Ireland in Hong Kong website for application procedures: http://www.consulateofireland.hk/

Honorary Consul of Ireland in Hong Kong, China
c/o Heidrick & Struggles
54/F Bank of China Tower
1 Garden Road, Central
Hong Kong
Tel: (+852) 2527 4897
Fax: (+852) 2824 9127
Email: info@consulateofireland.hk
Website: www.consulateofireland.hk

Entry Visas for Northern Ireland (United Kingdom):
Persons who are holders of a British Hong Kong Passport who have a right of abode in Hong Kong only do not require entry visas. 

Persons who are holders of a Hong Kong Certificate of Identity require an entry visa and should refer to the British Consulate-General in Hong Kong.

British Consulate-General in Hong Kong, China
Visa Section
Level 2 (entrance on Justice Drive)
1 Supreme Court Road
Hong Kong
(PO Box 528)
Tel:  From HK 800 938 671 (toll-free)
From Macao 0800 781 (toll-free)
From Mainland China 4008 855 899 (toll-free)
From Elsewhere +86 21 3882 4727
Fax: (852) 2901 3347
Email: visa@bcg.org.hk
Opening Hours:
08.45–11.00 for applications and 15.30–16.30 for collections, Mon to Fri,
except public holidays

Customs
Visitors to Ireland from the United Kingdom and other EU countries are not required to make a declaration to customs at their place of entry. However, certain goods are prohibited or restricted to protect health and the environment; restricted goods include meat and poultry. 

Customs operate green and red channels at most ports and airports. If you need to declare goods over the duty and tax-free allowances for non-EU visitors you must use the red channel. Pass through the green channel if you have nothing to declare.   

For goods obtained within the EU 
Although there are now no limits imposed on importing tobacco and alcohol products from one EU country to another, travellers should note that they may be required to prove at customs that the goods purchased are for personal use only. 

For goods obtained outside the EU 
The following goods may be imported by persons over the age of 17 without incurring customs duty:

• 800 cigarettes or 400 cigarillos or 200 cigars or 1kg of tobacco; 
• 10 liters of spirits (more than 22%) or 20 liters of intermediate products (eg port, sherry, etc, but not sparkling wine) or
• 90 liters of wine (of which only 60l can be sparkling) or 110 liters of beer; 
• 50g of perfume and 250ml of eau de toilette; 
• other dutiable goods to the value of Euro 40.63.