The Drowner's Map is one of the first you'll find in Kingdom Come: Deliverance 2, introducing you to the whole map mechanic for finding hidden treasures. This one isn't too difficult to solve, though as with other maps, it's poorly drawn to say the least—I guess Medieval mapmaking wasn't the most exact science.
You'll pick up the Drowner's Map from an unfortunate submerged treasure hunter who was looking to claim the fabled water goblin's plunder for himself. Luckily for you, he wasn't successful and so you can liberate the map from his somewhat soggy corpse. For those who are stumped or want to know where the treasure is, I'll explain its exact location on the map and how to reach it.
Drowner's Map treasure location
This really is a badly drawn map—it makes it look like the treasure is on top of a hill when it's actually in the water of a lake. You can find the drowner's treasure along the southern shore of Rocktower Pond; the big body of water in the west of the map where you first camp during the prologue.
The location is called the Water Goblin's Treasure. You can see it on the map above, but the best way to get there is to head west from Zhelejov on the path that passes Bozhena's shack along the shore.
You'll then have to dismount where the trail ends and start wading through the reeds. Continue a little way on, sticking close to the shore, and before long you'll spot a little clay pot on your left which resembles the one on the Drowner's Map.
Open it up and you'll get 125 Groschen—probably not worth the effort it takes to solve to be honest, but every bit of coin helps early on. If you want to see the water goblin's abode for yourself, the Water Goblin's Hut location is on the opposite side of Rocktower Pond, a little further on.
