P&O's excursion 'St Kitts railway and cruise' was the most enjoyable excursion I have ever done on any cruise. A catamaran takes you (at a very leisurely pace, and with plenty of alcoholic sustenance to hand!) along the beautiful west coast from Basseterre to near the base of Brimstone Hill Fortress (distant view only, but its huge scale is apparent). You are then transferred to the famous St Kitts scenic railway, which is unforgettable, before being transferred back to the port. An idyllic combination, if P&O are offering it on your cruise. Basseterre is also really charming. (You may have guessed that St Kitts is my favourite Caribbean island!)