Not really a travel gripe?
What do you want to do? Nothing is okay sometime.
On our recent trip we went for a tequila tasting at Casa Mission, in Belize we flew to Ambergis Caye and did a snorkeling trip, and at Mahogany Bay we just hung out on the beach.
Like Donna said, you can start with the Carnival excursions. Then search for tourism websites for your destinations. You can also look for independent tour sites such as viator. Search the term shore excursions and add your destination.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014, 2016
Star Clippers: Royal Clipper 2015