I have an undergrad degree in oceanography (earth & ocean sciences), finished my PhD last year, and now teach as a lecturer. I came here to make both of the above points. The career prospects in marine biology are abysmal for those with PhDs and even more so for those with only undergrad degrees. Minimize debt as much as possible. Run, don’t walk, toward an affordable option for undergrad. If U Hawaii is not to her liking, consider one of the other excellent options among the WICHE/WUE schools, like Western Washington, Humboldt State, or one of the other CSUs.
http://wue.wiche.edu/search_results.jsp?searchType=all
If she’s interested in Australian marine fauna, there are many excellent study abroad options in Australia. James Cook in particular is a superb option for marine science.
Regardless of the college she attends, she should take advantage of the many REU programs in oceanography. It was the REU program I did after my sophomore year that really prepared me for graduate school, I think.
https://www.nsf.gov/crssprgm/reu/list_result.jsp?unitid=5053
I always recommend that any student interested in marine biology get as broad an education in the sciences as possible. You don’t need a marine biology as an undergrad or even to study at a college on the coast; there are hundreds of colleges that provide perfectly good preparation for PhD programs in marine science.
If she attends an American school, picking up a minor or second major in something like CS or GIS/geography would benefit her career prospects enormously. As a rising high school junior, she still has plenty of time to settle on majors, though.