I am an exchange student from the US studying in Costa Rica. I am currently working on a research project investigating how the culture of the Southern Caribbean affects ecotourism. The paper is supposed discuss some aspect of ecotourism in Costa Rica, either by local or foreign tourists. I am having trouble deciding how to structure the paper. Any help or advice would be greatly appreciated.

Here, I think that the key structural issue with which you are struggling is focus. In other words, a good paper needs to be have a narrow topic and a clear sense of how you are approaching that topic. There are several ways you could focus your paper:
History of ecotourism in Costa Rica: With this focus, you could look at the evolution of ecotourism in Costa Rica from the 1980s to the present. You would begin by defining ecotourism and then survey its evolution chronologically, highlighting the ways in which Costa Rica has differed from other regions in its level of environmental commitments and policies. 
Compare and contrast: In such a paper you might compare and contrast ecotourism and environmental policies in Costa Rica with those in other islands in the region. In such a paper you would begin with an overview of ecotourism in Costa Rica and compare and contrast it with each of three or four neighboring nations, organizing the main body of the paper by nation.
Marketing: If you are studying business, you might write a paper about the market potential of ecotourism and how Costa Rica's unique level of environmental commitment can attract tourists. You could organize such a paper two ways, either by type of activity or type of tourist (broken down by demographic groups). 
https://unu.edu/publications/articles/ethics-and-environmentalism-costa-ricas-lesson.html