In chapter 5 of Might & Magic Heroes: Era of Chaos there is a hidden award: a chest with 100 diamonds. In this guide you will learn how to find it.
This is a side quest, which is available in the fifth chapter of the main game campaign. Click the scroll icon in the upper left corner to see the requirements:
In my case, next to the award, there was the inscription “No evidence found” all the time, although I was sure I did my best in the game.
But, as it turned out, not everything: the only character left on the map (elf girl), very talkative. She has something to say, but in the end, she will give you a hint. Just click on her until she tells you the location of the chest:
However, even knowing the exact location, I did not fully understand where the chest was. But I pressed the lake over the girl, and there really was a sunken chest. You can see it by carefully examining the screenshot below: