pilot fish:Nice link, thanks. What are the depths? Are there dive ops you can rent a drysuit from in each county and what is the cost?
The wrecks vary in depth throughout the country. For example the wreck of the U-boat near Baltimore (I forget the actual U-number) is 38-45m where as the wreck of the Bolivar in Dublin Bay has a max depth of 12m. You will definately find something that suits your level & experience.
The best thing to do would be to find a dive centre in the area you plan to visit (if Dublin, I would recommend Oceandivers). They should be able to provide you with a local orientation, boat trips to wreck etc before recommending another centre in the next place you are visiting.
The temperatures in the Irish Sea range from 6C in winter to 17C in Summer. Due to the Gulf Stream, Atlantic temps are normally slightly higher than this. Therefore a dry-suit is only really needed in winter. Some centres do rent them but you would need to contact centres directly. Generally, divers here use semi-dry suits (two piece 7mm neoprene usually) which are comfortable for the most part of the year. Most centres rent these for around 15. If you're interested in the sites or further info PM me.