I noticed the water is still not rendering right all the time. But it got me thinking. A number of years back there was under a billion dollar investment into Ocean-mining. But the costs outweighed the gains. Currently there are two companies exploring it again, since the oil industry advanced the technology. So what does this have to do with Boundless?
Aquatic survival, mining, farming, and settlements. How? A skill or device or potion that allows breathing underwater. (In reality the oxygen content in water compared to atmosphere would severely limit our exertion) This opens up a fairly unique avenue of game play to the people. Minecraft has this, sort of, but it is very undeveloped. There could be entire underwater biomes. Deep sea trenches filled with eldrich horrors. Entire agricultural centers underwater.
What weapons and materials would be used underwater? Projectile weapons won't work. Even a .50 cal bmg won't go very far in water. Harpoon guns are a tad advanced for a fantasy setting , but not implausible in Boundless. Harpoons, spears, knives, small swords, clawed gauntlets / bladed gauntlets and above water: grappling hooks. Surprisingly not tridents, tridents are a tool. Not needed or suitable to large targets, they are made to hit fast fishies, not needed for large targets.
Water resistance change movement and combat. No hammers, maces, axes, halberds, or shields. A swordbreaker gauntlet would be an ideal defense. Draw or push cuts would be effective underwater.
However, even though you can mine, you can't smelt or work metal underwater. Not without magic or advanced technology. Alternative options : teeth, bone, shell/chitin, stone, fibrous material.
I can see an entire underwater city in the future...