According to ancient legends, there are four lost cities under the lake. While a lot of the myth is just that, it does appear that the lake changed level at some point and flooded out the civilization that previously lived along its shores. Treasure hunters and archaeologists have worked the area for centuries looking to validate the legends and get rich at the same time. While they have made some interesting finds, it's likely that the four "cities" were really just villages of some sort. I would assume that these coins and artifacts belonged to the people who lived there before the shoreline rose.
Nowadays, the shoreline is dropping by about 2 inches a year, so lots of previously deep areas are gradually becoming accessible.
For those not familiar with this particular lake, it's the second largest mountain lake on the planet, and it's about the size of Lake Ontario.
Ive always been into artifacts and treasure, havent found much but a few arrowheads:
I wonder what those brass daggers look like.
Sounds like the Quabbin Reservoir in Mass. There are four lost towns under that man-made lake, but alas, no gold yet.