My experience traveling to tropical countries is that there is no good local chocolate - at least of the kind we are most familiar with here in the US - because it's just too darned hot all the time. However, you may find some chocolate that's made in other countries that does not make it into the US on a regular basis in Duty Free shops.
I know that cocoa can be grown in these places because they are in the correct latitudes, but none of them are known as producing countries. If you do find chocolate, it will probably be in some form that's similar to that found in other hot countries (e.g., a ball that is grated to make hot chocolate with), or incorporated into some local specialty.
If you do find some, make sure to take and post photos. Oh, and take and post some photos anyway - I know I'd like to see some tropical scenery right about now as it was 19 degrees F this morning when I woke up.