Prohibited anchorage area - telegraphic cable reserve [1907-1924]
The area is shown on map 1923 at http://www.hkmaps.hk/mapviewer.html. Does anyone know why ships weren't allowed to anchor here? [Update: because there were telegraph cables on the seabed here, that could be damaged by ships' anchors - see comments below for details.]
There's a description of its boundaries on p.504 of the 1925 book, Asiatic Pilot: The western shores of the China Sea from Singapore Strait to and including Hong Kong:
Prohibited anchorages—Lights.—The prohibited anchorage between the northern point of Hongkong Island and the southeastern point of Kowloon Peninsula is marked as follows:
Two white beacons on the shores of Kowloon and Hongkong Island, and two white masonry obelisks, situated northwestward and southeastward of them, respectively; when the beacons are in range with the obelisks, bearing 333° and 153°, respectively, they indicate the boundaries of the prohibited anchorage lines 300 yards apart.
By day the four beacons forming the front marks may be distinguished by their each carrying a red diamond shape; by night each displays a red light.
The lights are so screened that the easternmost lights do not show to the eastward nor the westernmost lights to the westward of the prohibited area; when, therefore, the two lights on the same side are visible at the same time, vessels must proceed until one or other of the lights is obscured before anchoring.
The southeast obelisk is shown in the top left corner of this photo, and the diamond for its beacon is above the right-hand 'o' of the watermark.