This page of the Assassin's Creed Valhalla Wrath of the Druids guide will show you how to unlock a new region - Ireland.
Before you can set sail for Ireland, you will have to build a new building in Ravensthorpe, the Irish Outpost, which is connected with the main quest Irish Trade.
First trip to Ireland
If you are ready to take on a new challenge, tell Azar that you want to travel to Ireland. You will, of course, be able to return to Ravensthorpe at any time.
Fast travel to Ireland
It should be noted here that after your first trip to Ireland, you will unlock the option to fast travel to the new region of Assassin's Creed Valhalla. Simply open the game menu, go to the World Atlas and select the Ireland region.