Ok. You meet some head gypsy or something. He says something along the lines of, "There is another power in these islands. Stronger than Jolly Roger" or something of that sort. Anyway, he (or she) sends you to all the different gypsies in the islands. They send you on different quests; retrieve a few things, kill a few minor bosses.
Towards the end you fight some UNIQUE bosses throughout the islands: Python for cuba, Giant hermit crab for tortuga, Etc. In the end, a new island appears, and you see.... Calypso!
Anyway, you fight your way up the island, fighting past swarms of enemies. NEW enemies and eventually fight Calypso.... level 99?