The Cyprus Pound is used on board ship as well as major credit cards. Currency is exchanged at the Purser's Desk.

On some ships the "Cashless System" has been introduced whereby on first boarding the vessel a deposit per person is lodged with the Purser's Desk in either cash or credit card and a special card is issued to you, to be used on board only. On completion of the cruise your statement showing all your purchases on board is printed and settlement is effected.

Cyprus pound is readily accepted in Egypt so small denomination notes is a must as it helps  bartering with the locals. 

The Euro is in use for cruises to the Greek Islands.