When you go to Xixi girl's place, there will be a combination of red dot NPC or trench on the seabed map. Go through Xixi girl and get on the boat. There are two blue dots that can enter the 1 layer. 1 Lou needs to kill and eat before I can get lobster. The overlord fish that lures away the gambling gate hits 2, 2, 3, and you need to answer the question wrong three times to kill the lost water ghost.