The Kid Who Vanished Sukhothai fieldwork will automatically start after visiting Tongdang’s hut near the start of the main quest here. We will head south to the treehouse area and make our way through some ruins to enter the treehouse itself, where we need to collect a couple notes as clues to where the missing kid went.
The clues point to Wat Si Sawai, which will be marked on our map. So head over to this area and enter the temple to find the kid. This will involve a couple basic water pipe puzzles, where we need to turn the water on and move nearby pipe pieces to complete the connections to allow the water to flow.
The final pipe puzzle is a bit more complicated, so we will start by climbing up the left and right side of the main room to turn on the water and find a pipe piece on each side. We can also search the room to the right for another pipe piece. Then with the three pieces, we will connect the pipes to the room on the left to open the door. Inside will be our final pipe piece for the puzzle. Once we have all four pieces we can complete the puzzle by connecting the pipes to the three grates at the opposite end of the room. This will finally reunite us with the kid and after meeting with him we can return to Sunan in the main village to complete this fieldwork.