A Master’s Degree In Plumbing
Great Bay Temple’s layout is cryptic at the best of times. Invariably you will be lost as to which underwater tunnel leads where. Thankfully, the 3D remake has a good method to lead you to where you go next; pipes going in and out of tunnels light up based on whether the pipe is receiving any water or not. So, a good way to start in the temple is to go to any underwater tunnel that has a pipe running out of it that doesn’t have water in it.
If you still need help, your map actually tracks where pipes go as long as they have water running through them. Tap on it to zoom in, and the map will give you a detailed view of each room, including valves and their current orientation as well as active pipes.
If you STILL need help after that, you’re not alone, Great Bay Temple is just very poorly designed. Just pay special attention to your map and double-check everywhere.