Traveling from the UK to Ireland is exceptionally easy and offers multiple modes of transport depending on your budget and preference for speed. The fastest way is by air; dozens of daily flights connect major UK cities like London, Manchester, Birmingham, and Edinburgh to Dublin, Cork, Shannon, and Knock. For those who prefer a more scenic or "slow" journey, the "Sail & Rail" tickets are a popular choice. You can take a train to Holyhead or Fishguard in Wales, or Liverpool in England, and then board a high-speed ferry operated by Stena Line or Irish Ferries. The Holyhead-to-Dublin crossing is the most frequent, taking about 2 to 3 hours. From Scotland, you can take a ferry from Cairnryan to Belfast in Northern Ireland. Because of the Common Travel Area (CTA), British and Irish citizens do not usually need a passport for travel between the two countries, though they must carry a form of valid photo ID. For international visitors, a passport is mandatory. The connectivity is so high that it is common for business travelers to complete a round-trip from London to Dublin in a single day.