Final answer:
For a four to six-page research paper, 'why scuba diving is so popular' is a suitable topic that is interesting, precise and manageable. It allows for exploration into various facets such as environmental impacts and cultural significance, which are appropriate for the length of the paper.
Step-by-step explanation:
Choosing a research paper topic that is interesting, precise, and manageable is crucial, especially for a paper that is four to six pages in length. Among your options, a topic like 'why scuba diving is so popular' could be the best choice. This subject is not only interesting, but it also allows for exploration into a variety of aspects including cultural, psychological, and environmental factors. In contrast, topics like 'my experiences deep-sea fishing in the Pacific Ocean' may be too personal and lack the scholarly depth required for a research paper. 'Proper equipment for scuba diving' and 'how to navigate the ocean' could also be suitable topics, but they might be either too technical or broad, respectively, for a paper of this length.
When selecting your topic, consider factors that a marine ecologist might include in their studies, such as interactions in the ocean and marine ecosystems. Moreover, the popularity of scuba diving can be tied to broader issues such as conservation efforts, advancements in technology, and marine biodiversity, which could lead to a rich, multifaceted paper. To ensure the topic is manageable for the length of your paper, you may choose to focus on one key aspect of scuba diving's popularity, perhaps its role in tourism or its impact on marine life.