How do I get the piece in the pond?

The Sunken Gong Piece is the thirteenth puzzle in Virtual Villagers 2. First, you will need to have gotten Exploration level two, and pick up the pot in the wood pile. You will need to have completed puzzle 5, and have over ten food. Drag a villager to the pot, on your fire, and he'll start a stew. Drop him on it again, and he will get water. If you have three other villagers on hand, take one to the black flowers next to the graveyard. This villager will take one herb from this plant and put it in the stew. The others need to go to the red-orange flower at the bottom of the map, and they will bring the other herbs. You need three herbs for one stew. After the water and herbs are in the pot, drop a villager on the food bin, and he will carry food to the pot. Once everything is in, the stew will appear in front of the fire. Feed this stew to a villager, and put her in the pond. She will dive down, and in a few minutes, emerge with The Sunken Gong Piece. She will carry to the research lab, and it will be visible in your Collections.

Source:The Virtual Villigers Wiki