Sinking Islands / Buried treasure

[Owlrust]

I'll try to make this short so that people don't have to waste too much time reading.

What about randomly generated islands that appear all around the ocean in various places and sink after some time (maybe after a season?), to be replaced with different islands. They would more than likely have some stuff worthwhile exploring for and maybe buried treasure, or pirates that you must fend off, or something of the like.

[HowlVoid]

Oh! I've had a similar idea involving a volcano spewing molten magma and cooling on the ocean forming walkable land. Summer is a bit unimpressive at the moment at I got my idea from the "ash" islands in shipwrecked. You know, the ones with a bunch of burnt trees and scorched rocky turf. 

Since it dissipates at the end of summer any structures you place to make the season more bearable will need to be placed again every summer. Not to mention boats will need to be smoldering proof. The volcano itself can be out of view and the land can be built by its meteors of lava. Could be a neat way to introduce obsidian to dst or minable gems. It can introduce giant bat enemies, molten lava monsters, and the occasional pirate monkey lol. Just overall very late game stuff.

[Frosty_Mentos]

Maybe map expansion for volcano biomes and such

[Cheggf]

How would a bunch of islands keep sinking and rising out of the sea? And why would pirates (which don't even fit the theme of the game at all) be on the islands? Makes no sense.