Activities are smaller quests that you can take in Kingdom Come: Deliverance (indicated by the exclamation marker icons on the map). Below you will find a list of activities that can be unlocked in Uzhitz and the surrounding area. It's a village in the north-east corner of the map, which you can visit on your own initiative or while completing the main quest Mysterious Ways.
Fishy Business in Uzhitz
How to unlock: Talk with a fisherman in the camp who resides in north-east area from Uzhitz.
You have to visit the camp site located to the northeast of Uzhitz - its location is shown in the screenshot above. Talk to a Fisherman to learn about money fights.
Before you can challenge a fisherman to a duel, you must fight three other warriors from Uzhitz. Each time you challenge someone to a duel, the action will switch to a small arena next to the village. The fight takes place without the use of weapons, so it is worth to take care of the leveling close combat (Unarmed) skills beforehand. You can also successfully develop this skill by playing this quest. You have to pay 5 groschen before each fight, but after the victory you will win 10 groschen. You can search the body of a defeated opponent and take valuable things from his inventory.
For defeating a fisherman, you will get a skill book (Agile as a Weasel), which increases Agility after reading it. The quest itself will not end yet. You can challenge the fisherman once again to further develop Unarmed skill (he also offers paid training in this field).