Ning Fan did not dive directly into the bottom of the Boundary River in front of the cultivators of Lingyun Pass. Instead, he flew far away from it before plunging into the river.
Diving to the river bottom was a terrifying action, akin to courting death in the eyes of the Eastern Celestial Cultivators. Ning Fan did not want to shake the morale of Lingyun Pass because of this.
Ning Fan knew well that the riverbed was extremely dangerous. However... hadn't he captured a mermaid empress named Aflo and obtained a lot of intelligence about the Boundary River from her? Therefore, he was quite confident in moving freely beneath the river.
He already possessed seven Dragon-Horse True Spirits, but because they did not cultivate divine sense, he could not retrieve memory.
Aflo, being from a different race, also did not cultivate divine sense. However, by combining Mind Reading Technique and bewitching technique, Ning Fan was able to gather a lot of intelligence from Aflo's mind.
