This is a Daily Alpha Update. Developers release them every day, and this is the one for 12/16/2013.
Today is the second day of our Mysterious Week, mates! I bet you are eager to see what the mysterious update is right now. Before I dare tell you what it is, let me first say it has a blue land. A blue land? What kind of update would have a blue land? Oh, of course! An island has a blue land.
Please welcome the second mysterious island with the "blue land" I mentioned.
(To not confuse you, the blue area is probably the water around the island. I figured it was water but eh, why not I call it a "blue land" :P)
Like TheGleamings said, they all look similar but they are different. If we do happen to release all of these mysterious islands into Pirates Online Rewritten, you'll seek their differences. Even different than Raven's Cove. Yet, you'll still have a great pirate adventure!
Before I leave, let me remind you to be sure to tell yourself this: Very mysterious!