Hm... I was fooling around when I noticed a thing...
When I was trying to do a not-related-to-banjo-anyway thing (changing a Neo Geo emulator... with no sucess), I tryed to do in Project 64 and BK.
Using the RWP sandcastle codes and the Project64 "Have All Secret Items" cheat, I noticed that, if a certain memory adress is between 8 and 15, Sharkfood Island will rise. If it is zero between 7 or 16 between 255, Sharkfood won't rise... It isn't a greeeeeeeeeeeat thing (probaly Ice already knew), but I posted here