Here are some things to do in Siesta Key, Florida in December:
Visit the beach: Siesta Key is known for its beaches, and December is a great time to relax in the warm sun. 

Watch the sunset: Sunset Point is a popular spot to watch the sunset in the northern part of Siesta Beach. 

Go parasailing: Parasailing is a fun and safe water sport that combines the thrill of a powerboat ride with the tranquility of a hot air balloon flight. 

Explore Siesta Key Village: Stroll or bike through the village to shop, eat, and experience the Christmas cheer. 

Try the seafood: December is a great time to try some of the region's freshest seafood catches. 

Go on a dolphin cruise: Take a dolphin cruise while visiting Siesta Key. 

Go fishing: Try your luck at fishing. 

December is a popular time to visit Siesta Key because the weather is warm and sunny, making it a great escape from the cold. High temperatures in December are usually in the low-to-mid 70s