Mira, Maria, and Celaine started back on their journey after that little detour in the Mermaid City.
After getting back out to sea, the 3 of them were slightly tempted to try cultivating the Water Body Transformation technique, but the thought of imploding made them stop.
They also became slightly depressed after entering back into the ocean as it was pitch black, they can't breathe like normal, they are constantly being watched and attacked, and it's highly unlikely that they'll find something good in this situation.
They decided to swim up to the surface to regain their bearings after staying in the Mermaid City for a few weeks.