In Cartagena, you can do the following activities:
- Go to the oldest film festival in Latin America (the Cartagena Film Festival).
- Do sports in Simón Bolívar Metropolitan Park.
- Attend the Festival of Flowers (although this festival mainly takes place in Medellín, some events may happen in Cartagena).
However, swimming in the Pacific Ocean is not applicable, as Cartagena is located on the Caribbean Coast of Colombia.
So, activities you can do in Cartagena specifically include:
- Go to the oldest film festival in Latin America.
- Do sports in Simón Bolívar Metropolitan Park.
- Attend the Festival of Flowers (though it's not primarily based in Cartagena, related activities might occur).
If you had to choose one from the list provided, the best option specific to Cartagena would be to go to the oldest film festival in Latin America.