[3] The Hydrographic Office also stated the entrance of the harbour lies between Lung Ha Wan (龍蝦灣; located in Clear Water Bay Peninsula) and [a] Peaked Rock [sic], with a width of about 1.5 miles (2.4 km).

[3] The islet itself is connected to Sharp Island (Kiu Tsui Chau; Chinese: 橋咀洲; Jyutping: kiu4 zeoi2 zau1; Cantonese Yale: kìuh jéui jāu) by a bank.

[6] Environmental Protection Department, partnered with local universities, also conducted water quality and phytoplankton research in the Port Shelter.

These islands are considered within the boundary of the water body of Inner Port Shelter:[8]: 607 The greater Port Shelter area receives discharge from Ho Chung River (蠔涌河), Tai Chung Hau Stream (大涌口溪), and Sha Kok Mei Stream (沙角尾溪),[11][12] as well as man-made storm outfalls and a submarine outfall from the Sai Kung Sewage Treatment Works.

[11] They concluded that in the inner [sic] Port Shelter, the flushing time is the longest among the fish culture zones of Hong Kong, which is 40 days in the dry season.

[11] While Po Toi O is located at the mouth of Port Shelter [sic], its hydrodynamics is mainly affected by the open ocean, thus the flushing time was just 5.3 days in dry season in the computer estimation.

Port Shelter was also mentioned in a report to the UK government in 1898 by James Stewart Lockhart, shortly after the signing of the Convention for the Extension of Hong Kong Territory.

[15] The Convention ceded Port Shelter and other areas that collectively known as the New Territories and New Kowloon, to the British Empire, as an extension of the colony of Hong Kong.

[18] The government also relocated the residents of Kau Sai Chau, an island in the firing range to the land area of Hebe Haven (known as Pak Sha Wan in the publication) in the 1950.

For the purpose of that regulation, they defined Port Shelter Area as:[31] The waters of Port Shelter bounded on the north and west by the mainland shore, on the south and east by a straight line drawn from position 22°20.111′N 114°16.207′E / 22.335183°N 114.270117°E / 22.335183; 114.270117 to the southern extremity of Sharp Island (Kiu Tsui Chau), thence by a straight line drawn true east to the shore of Kau Sai Chau at position 22°21.177′N 114°18.237′E / 22.352950°N 114.303950°E / 22.352950; 114.303950, thence along the western shore of Kau Sai Chau to a causeway at position 22°22.386′N 114°18.284′E / 22.373100°N 114.304733°E / 22.373100; 114.304733, thence along the southern side of the causeway to the southern shore of Yim Tin Tsai, thence along the western, northern, eastern and southern shore of Yim Tin Tsai, and the northern side of the causeway back to the shore of Kau Sai Chau, thence along the northern shore of Kau Sai Chau to the breakwater light of Yim Tin Tsai Typhoon Shelter, and thence by a straight line drawn true north to the mainland at position 22°23.144′N 114°18.401′E / 22.385733°N 114.306683°E / 22.385733; 114.306683.The specified sheltered water that defined from above coordinates and natural boundaries, actually covers the Inner Port Shelter and Hebe Haven but only part of Port Shelter, that defined by the publication of the U.S. Hydrographic Office, which draw the southern boundaries from Lung Ha Wan to a peaked rock south of Jin Island.

That regulation also defined "Port Shelter and Rocky Harbour Area" that cover all of the Port Shelter (and some part of Outer Port Shelter by some definitions) and Rocky Harbour:[31] The waters of Port Shelter and Rocky Harbour bounded on the north and west by the mainland shore and on the south and east by a straight line drawn from the eastern shore of Lung Ha Wan at position 22°18.632′N 114°18.199′E / 22.310533°N 114.303317°E / 22.310533; 114.303317 to the southern extremity of Ping Min Chau, thence by a straight line drawn to the north-westernmost point of Bluff Island (Sha Tong Hau Shan) at position 22°19.507′N 114°21.015′E / 22.325117°N 114.350250°E / 22.325117; 114.350250, thence by the northern shore of Bluff Island (Sha Tong Hau Shan) to its eastern extremity, and thence by a straight line drawn to the southernmost point of High Island (Leung Shuen Wan).