The area that was once the Mississippi river basin has flooded and become the Mist Sea. It is so called because a heavy fog covers it at all times. While not impossible, the Mist Sea is extremely difficult to navigate. Only a handful of ship captains know the waters well enough to sail across.

On the northern waters of the Mist Sea drift an unknown number of ancient massive shipping vessels that are now home to strange ecologies and even stranger inhabitants. Each is now completely overgrown by various types of heavy foliage and some even sport large trees. There is much conjecture on how this came to be but considering a good portion of the floating isles are inhabited by Faefolk, magic probably is to blame.

These artificial islands rarely come close to shore but the few times they have, a hoard of fae has descended upon the local populace. They prank, enchant, steal, and pillage until their home begins moving away from shore again. Those that live on the shores of the lake have learned to be very wary when any of the overgrown hulks venture anywhere near the shore.

When two or more of the isles come close to each other, more often than not they make war upon each other for as long as they are adjacent. These skirmishes are often violent and teeming with magic.

• While resting up in a pleasant little village on the shoreside, the party hears a cacophony of sirens fill the air. The locals are all panicking and pointing at an old, overgrown barge heading close to shore.
• The party’s quest for medicine for a sick ally has led them to seek rare herbs that are said to only grow in “floating fairy forests”. Now they have followed rumors to the shore and the infamous floating isles.
• The sweetheart of one of the party members has gone missing while searching the lakeshore for washed up treasures. Now they must investigate the isles to locate and rescue the sweetheart before it is too late!

Source: Umerican Survival Guide