You have two exams, theory and Lab. These occur about a week or so after you come back from Queenscliff. For the Lab, you really need to study and know your algae and your phytoplankton and know their defining features. Cannot stress this enough. I know a lot of the phytoplankton look pretty much the same under a microscope, but you really got to find the defining features like the extra flagella, or haptonema, or armour-like protection.
Theory Exam was much easier in my opinion, there isn't a whole tonne of stuff that needs to be learnt for the subject, and as long as you've been reading up and studying for this exam, you should be fine. And there are no pictures, which I was happy about, since distinguishing between different micro-organisms or algae on a picture is what caused me trouble.
Although I have listed some gripes with the subject, I still give it a 4 out of 5. I think its my favourite subject I've done at uni so far. You definitely get enthusiastic about this subject even if you're not someone super into plants and botany and stuff. I definitely recommend this subject, it only has a quota of 30 people, so don't leave enrolment to the last minute. It is very interesting, and you get to go to Queenscliff for 10 Days, which is good as. Its not too hard to score well, provided you don't make many careless errors. Having said that you still need to work for it though, just that there aren't difficult concepts to remember or anything. Anyway I hope this is helpful to all you prospective Marine Botany Students!