Howth is located 10miles north from the centre of Dublin. A boat ride to the island costs EUR 10.00 each and if you would like to get off the boat and see the island it is EUR 15.00 each. You can get to Howth by train from Dublin. Dublin Pearse station is near Trinity College and the trains to Howth run  every 30 minutes. The journey also takes about 30minutes. Once you are in Howth you just head towards the harbour and you will see signs for the boat journey. There are several of them.

Follow this link to visit the website of Irish Rail

Click here to visit the Official Tourism Site of Dublin