Jal lacks inhabitants and trees. Maybe in Jal, we could have crabs running around, but also some underwater plant life (that doesn't need any watering, of course!) that can be harvested! And then fishes. Fishes make the world go round.
Plant life ideas:
Seaweed Plant - Seaweed could probably used as an ingredient mostly for potions or food
Inhabitants ideas:
Giant oysters - They replace the street spirits of the region- but they are 'Luck Vendors', as you can buy small oysters, maybe each of different 'rank' (but also different price) and open them to try to find a pearl, or currants, or something.
Crabs - Just putting them there too
Fish - They could be like the equivalent of pigs in the overworld- Able to be nibbled to obtain Fish Filets.
Narwhals - Because yes
Please +1 if you support this idea and maybe suggest inhabitants or plants! I will put suggestions on the original post to keep it organized!