Regarding the choice of location for building Hope City's sub-city, Shuangshuang directly entrusted Yan Ming, asking him to use divination skill to select a suitable place—a site that won't easily be devastated by natural disasters after the city is constructed.
In fact, the place where the Fishman Clan lives is inherently the least likely to experience natural disasters. The Fishman Clan has lived in the sea for generations and possess a talent for sensing natural disasters.
The places the Fishman Clan chooses aren't entirely immune to natural disasters, but the probability is minimal compared to other areas, so building the sub-city next to the Fishman Clan is the best choice.
Sure enough, after Yan Ming's divination, the chosen location isn't far from the Fishman Clan's residence. Additionally, this site is quite impressive: a huge mountain on one side and a freshwater lake on the other, meaning Hope City's sub-city can be built right at the foot of the mountain.
