The warning tower was usually unoccupied, for Hill's Water Maze Lock extended far across the sea and defended from above and below, and with Water Elemental Sprites freely frolicking in the sea, there was simply no need for someone to be on watch in the tower.
Just like these elf ships, their easy access was possible because Hill had given permission in advance, otherwise, they would have faced impenetrable white mist and aggressive attacks from Water Elemental Sprites.
And the ships granted permission were guided by the diligent and adorable Water Elementals, completely obviating the need for harbor management to provide docking instructions.
However, during regular docking by merchant ships, List could handle things. The elf fleet presented too much of a risk, which is why Hill needed to manage it. In such cases, the Water mist would only obey Hill's will; his Tower Spirit was of no use.