Lola was already being pressured by these Sea Creatures and she knows that her city wouldn't last for long if the enemies decided to just send out their forces to invade them all at once.
In the end, she thought of communicating with the Sea King and reaching an agreement with it just like what the members of the Star Garden Peak have done.
Perhaps they can tell me to invade a different plot of land instead of starting on their city. She can even offer her help to conquer some other land if necessary just to make them stop.
However, she had to visit the Underwater City of this race in order to do that. The problem is that they have no way of breathing underwater just like what the members of the Star Garden Peak did.
They don't even have a Magic Artifact that could help them move in the water.