One can only say that wealthy families are truly grand; there are hidden doors and secret chambers everywhere, with several Cave Heaven Secret Realms to boot.
But it makes sense. The Lan Pond grows countless Golden Lotuses, which are actually rare treasures that can be harvested for Alchemy and Artifact Refining.
The Xiao Family further arranges these Golden Lotuses into a formation with a special Array; without a talisman to drive the boat, it's impossible to enter or exit the Golden Lotus Array. Without knowledge of the Array Technique, one who intrudes rashly will be entangled by flower stems and roots, potentially drowning in the mire. Even yin souls are barred outside this many-layered Golden Lotus Array, unable to step in.
However, with the Kun leading the way, swimming ahOéad and pointing directions among the water plants and fake mountains, Tie Dan recites the water avoidance art and follows in unnoticed, stealthily entering the Lan Pond.