Undercurrents

There is a hidden world under the surface of Bohemia but it is not exactly what you would expect. Undercurrents is the overall term for the networks of underground rivers, lakes, cave systems and hidden ponds. Some of them even connect to the Lagoon layer of Whatif. It's around those bubbles connecting two layers of reality where the most notorious magical watermonsters reside.
The richest flora and fauna is usually concentrated in cavern systems under huge and mostly unexplored mountains, far away from industrialised and human populated towns and cities. Quiet seems to be beneficial to these ecosystems. That and the cold and darkness.
When it comes to flora, there are various species of water lilies, reeds, acorus and calthas to be found, there are several species of upturned trees whose leaves and fruits you can find only in the underground. There also plenty of weird mushrooms around, some fluorescent, some magical, some poisonous, some delicious - and some all of the above. When it comes to fauna, it gets trickier to monitor as majority of species do not like to be disturbed and mostly just run away, and those fish that do not, get eaten. However, the deeper you go, the weirder and more tentacly friends you will be able to find. Nymphs and water sprites and vodyanoi included. Be careful not to lose your soul while diving and bring some pretty mugs as a toll to pass to more interesting caves. If you're lucky you might even find some treasures. Just stay away from anything resembling a goldfish.
There are also many artificial ponds as aquaculture and keeping fish as a source of food is very popular in landlocked Bohemia. There are usually diplomatic treaties to be negotiated and signed with the various water nations who reside in the natural springs and streams around. Ponds that do not follow this process usually end up dry pretty quickly if they are not connected to the rest of the nearby water networks.