The first in the M series of D&D Master Rules adventure modules, this is a pretty cool one! Demanding a really high level party (you should have 150 levels in total among players) this adventure will pit you against the gods of the known world and throw you into the titular Maelstrom which is really a portal to adventure.

There is something familiar here in having ships that float through space but are still apparently seafaring ships. Well, we are still some years away from Spelljammer but there sure seems to be a huge similarity between what you do in this module and the Astral travelling setting. 

I’d honestly be surprised if Jeff Grubb didn’t take some inspiration from this when he was thinking up Spelljammer, there are enough differences for it not to be a full lift, but there’s a certain feel that does make the two ideas rhyme. This module has some really cool interior illustrations by Valerie Valusek, as well. Worth taking a look!