Here are some links to the more popular holiday destinations that require visas. The list is not conclusive. The information is subject to change and is valid for Irish passport holders.
America
https://esta.cbp.dhs.gov/
Must be applied for at least 72 hours in advance. Costs $14 USD.
There are many unofficial websites offering visa services that cost much more so please always use the official website.
Canada
https://www.canada.ca/en/immigration-refugees-citizenship/services/visit-canada/eta/apply.html
Approval time varies from instant approval to approximately 72 hours.
Costs $7 Canadian dollars
Australia
https://uk.embassy.gov.au/lhlh/IMMI_holiday_info_eng.html
Evisa applications are done via the London office. Evisa is Free and usually processed within 2 days.
New Zealand
https://www.immigration.govt.nz/new-zealand-visas/apply-for-a-visa/about-visa/nzeta
Evisa applies as Ireland is listed under visa waiver.
Costs $12 New Zealand Dollars.
Approval time varies from instant approval to approximately 72 hours.
India
https://indianvisaonline.gov.in/evisa/tvoa.html
For Cruises – you need to ensure that all ports on your itinerary accept the evisa.
Cost $25 – $40 USD depending on number of entries required (each port on a cruise counts as one entry).
Must apply at least 4 days before travel.
Russia – St. Petersburg
https://evisa.kdmid.ru/
Can only be used for St. Petersburg. Allows for a maximum of 8 days in St. Petersburg but not valid for general travel around Russia. Free. Only Valid for 30 days from date of issue. Can take up to 4 days to authorise.
For all other passport holders follow the links above and ensure your passport meets the criteria for a visa or electronic visa (evisa) to the relevant country. Alternatively, contact the embassy in question.