The reason why flying boats are used to carry ores on the Westward Bay is because of the chaotic True Qi. The ordinary spatial rings can't bear the burden of tons of mineral ores.
As for Westward Bay, the water is dense and filled with chaotic True Qi. The True Qi is hard to absorb on the Westward Bay unless it is purified by a higher rank cultivator or a Qi Refining Formation.
Even cultivators of the Harmonization Realm will face difficulties in absorbing qi from Westward Bay directly.
Now, a good question. What will happen if the cultivators get buried thousands of meters underground in a mine that requires True Qi to get mined?
For low level cultivators, they will die like ordinary people under suffocation. Only those with higher cultivation realms or Earth attribute techniques can escape from this calamity.
But then, What will happen if their reaction time gets slowed or they get paralyzed?