With Christmas, literally around the corner, I was reminded of a cruise my sister took that included Easter. The port of call for the day was Martinique. She booked a shore excursion that turned out to be 'adjusted' for the holiday....everything was closed. She was livid and expressed her strong opinion to the tour excursion desk where they did refund her money.
While it should have dawned on her that Easter would be celebrated on Martinique, the fact is there are local holidays we would know nothing about unless we did our research. Some times we would love to be there at festival time like when my friend and I went to see the annual National Day of the Ox Cart Driver in Costa Rica.
Other times though, when our time is limited, we might want to reroute ourselves so we are not in a city when all the museums. If something or someplace is important to you on your travel, check to make sure there are no special events on the day you will be there. Books like Frommer's where I linked to above, are a good place to start your research.