Thank you! This means so much to me i am honoured to hear that inspire you :)
Ive been getting alot of questions about this recently so i will post this for anyone interested :)
A good background in biology is important if you want to specifically do marine biology (so during your tertiary study take biology papers- more the ecology side) My degree is Marine science and biology. However you can also mix it with geography and statistics depending what you enjoy more.
Other subjects that are important are geography and statistics (these are also compulsory in NZ for all majors but they only need to be taken broadly) environmental science and chemistry are also helpful. Geology may also be of use.
It is strongly recommend to have a background in chemistry i have found that from doing chemistry during high school and my first year I havent found any problems with any of the chemistry side of Marine study, yet anyway.
Physics is only lightly recommended but can help with some of the oceanography concepts the only physics i have done is one paper at university and i have been fine.
In respect to what exactly a marine biologist does.. it can range from research to conservation work to fisheries management, oceanography, exploration to television work as guest scientists and lecturing.. there is honestly a huge range of potential employment i personally want to do abroad research when i finish my degree.. its my life goal to study in Antarctica, with any luck it shall happen
Good luck in your own study i hope i was of help :)