The main and favourable way to see best sites of Dublin in an afternoon are the tour buses. not only do you get to see some of the most famous landmarks of Dublin, but you also have a running and detailed commentary. The tour operates on a hop on hop off basis, meaning you can get on at Trinity College and alight at Christ Church for example, its up to you! In Dublin there are two major sightseeing Bus tours to choose from, Dublin Bus Tours and Dublin Tour. The approximate prices are €15 for adults and €7.50 for children under 12 years.
If you are looking for an alternative way to see Dublin, we recommend Viking Splash Tours. On the Viking tour you learn how the Vikings left their mark on Dublin. Included on the tour is Christchurch, Trinity College, Merrion Square and more. At the end of the tour you will splash into the Grand Canal Harbour to continue by water in their amphibious vehicle.
If you are feeling adventurous and are interested in seeing Dublin from a new angle, Sea Safari is just for you. Sea Safari powerboats depart from Dublin city on the rive Liffey and Malahide Marine, bring you on to see lambay Island, Ireland’s Eye, Howth Head, Kiliney Bay and much more, given you the chance to some of the coastline wildlife including seals. Lifejackets and all weather clothing are provided.
There are also walking tours around popular locations in Dublin. Dublin city centre is not huge, any active person could walk around the city centre within 2 hours.