The teeth and fingerbones of holy men and more
The Pool of (add the name of the God or Goddess of your choice) is well known as one of the greatest holy places of the world. It is said to be full of piles of gold and jewels, a place where wishes are granted, wounds are healed, prophets have dreams that come true, and suspected criminals are fairly judged. Pilgrims from the other end of the world have been known to travel for more then a year, braving the perils of disease, brigands and bad weather, just to reach it's holy waters.
A friendly human hunter has a talk with you about what you are doing here, and how is the weather. He advises you to not disturb the animals, tend to any fire you set, etc. This is actually a werewolf checking his territory, and if you are not to his liking, he may ambush you with his pack later.