Indeed you did, I've thought of a aquatic blackmoor/wilderlands for the last couple of days and started to brew a few new race/classes including a humanoid that seemed more fish then man but perfectly blended features and a few other ideas I got from recent reads. Also had monsters on the brain and was thinking hpow could X become Y and first thought 'Egg of Coot tends to toss out failures, maybe they spawned more failures and became a quasi sentient race or species of horrors?' So I broke out the metamorphica for unique mutations and ideas for chaos spawned horrors of the deep. I also used a class from Theory and Thaumaturgy called the Vivamancer to represent my npc 'breeders' who release the spawns or melt them down for plasm.

I finally got the chance to run a one shot with friends set in Blackmoor below the waves of the Black Sea. One played my Homo Amphibious and the other a weird little kobold like creature that was aquatic(Coots attempt to mix kobolds and aquatic dinosaurs to get adorable pets that got annoying). They both come too in the 'Lab' a large construct at the oceans bottom and after maneuvering through its defenses(robots and wizards) they find themselves at a large pool of water and upon instinct dive in to flee from their chasers. Soon after fleeing to a safe 'place' they begin to lick their wounds and encountered a Tylosaurus who smelling the blood grew hungry for a snack. This encounter ended with them trying to escape though the cave they were hiding in. Turns out the player playing the Homo Amphibious didnt noticed the spells he had access to including one that drew the oxygen from the water around a target. The magic system for him was a bit similar to blood magic though, the more he cast spells outside his reach the more he devolves or mutates. The weird kobold thing had no spells or combat abilities except minor empathy that influenced their base stock, dinosaurs! They encountered merfolk hunters who through careful diplomatic relationships/fear didnt kill them on site but did slay the Tylosaurus since it was a creature bred of Coots experiments. Most encounters were weird aquatic things and dinosaurs, it lacked a lot of luster and I saw some things I needed to fix with the classes I designed including the mutate/devolving rules and encounter tables, they lacked flavorful events. The game ended with them in Frog Swamp some how.

Love that you tested out this concept. :-)

-Havard

These could be suitable underwater settlements for "the last days of Blackmoor" campaign scenarios:

I wander if after the Rain of Fire there is anything worth of mention left under the waves...;-)

Well, you know that in the LFC, the Sar-Aigu are basically Merfolk. Granted, they only get a cameo, but this is what I operated with all along.

Within the (official, you damn Mystaroons) continuity of Wilderlands and Blackmoor, the connection between the Sar-Aigu and the Viridians (basically the same concept, both being sea-based forefathers of civlization) you can do a lot of stuff, from the frogmen being their bred henchmen, to the (overall and very basic) similarity of their ancient history.

Now, I am not developing that concept all too much further, but it might be worth a look to you guys.

Many many years ago I had a DM that was especially good with underwater adventures... I think it can be a really cool setting for campaigns and not just for the odd episode :D

Maritime / naval fantasy surely is an art form. The older I get, the more I find myself drawn to the subject.