Dangerous Ground (South China Sea)

Dangerous Ground
Dangerous Ground
	Map of the South China Sea area showing the location of Dangerous Ground
	Dangerous Ground
Coordinates	10°N115°E / 10°N 115°E
Part of	South China Sea
Max. length	340 nmi (630 km)
Max. width	175 nmi (324 km)
Surface area	52,000 sq nmi (180,000 km2)
Islands	Spratly Islands

Last updated September 07, 2024

Map showing the areas covered by NGA charts Pub161-pg1.jpg — Map showing the areas covered by NGA charts

Dangerous Ground is a large area in the southeast part of the South China Sea characterized by many low islands and cays, sunken reefs, and atolls awash, with reefs often rising abruptly from ocean depths greater than 1,000 metres (3,300 ft).

There are few precise definitions, but Dangerous Ground corresponds roughly to the seas around the eastern half of the Spratly Islands. It is an oblong area running southwest to northeast for about 340 nautical miles (nm) (630 km), 175 nm (324 km) at its widest, with an area of about 52,000 nm² (178,000 km²).^[1] It is west of Palawan island and northwest of the Palawan Passage. It lies approximately between 7.5 and 12°N, 113–117°E. The US NGA literature^[1]^[2]^[3]^etc. seems to consider its centre as 10°N115°E / 10°N 115°E / 10; 115 .

The area is poorly charted, making it exceptionally dangerous to navigate – the major Singapore-to-Hong-Kong routes go well to the west^[4] and east of the area. The Admiralty Sailing Directions^[5] give the following warning regarding navigation in this area:

Due to the conflicting dates and accuracy of the various partial surveys of Dangerous Ground, certain shoals and reefs may appear on one chart, but not on another regardless of the scales involved.
Charted depths and their locations may present considerable error in the lesser known regions of this area. Avoidance of Dangerous Ground is the mariner’s only assurance of safety.^[1]

The water is a usually greenish-blue and is transparent to depths of 24–42 metres (79–138 ft) on clear days.^[1]

Boundaries

The boundary of Dangerous Ground is shown on NGA charts 93044 (NW),^[2] 93045 (NE),^[3] 93046 (most of the SE),^[6] and 93047 (SW).^[7] (The missing portion of the SE is covered by 93048^{[note 1]} and the top corner of 92006.^[5])

The area is described in NGA Pub. 161, Sailing Directions (Enroute) South China Sea and the Gulf of Thailand.^[1] The navigational charts and sailing directions do not completely agree with each other as to the boundary. For example, the Sailing Directions include most of the NW area shown on Chart 93044 as outside of Dangerous ground, but exclude the Reed Bank, which is shown on Chart 93045 as inside Dangerous Ground.

Both publications divide the area into four quadrants - NW, NE, SE and SW:

NW

Chart 93044 – approx. 10–12°N, 113–115°E;^[2]Sailing Directions pp8–10.^[1]

1.21 North Danger Reef – northern and western sections
- North Reef, North Pass, Northeast Cay, Shira Islet, Middle Pass, Southwest Cay, West Pass (N), Jenkins Patches, West Pass (S)
1.22 North Danger Reef – southern and eastern sections; Trident & Lys Shoals
- South Reef, South Pass, Sabine Patches, Farquharson Patches, East Pass, Day Shoal, Iroquois Ridge; Trident Shoal, Lys Shoal
1.23 Thitu Reefs and surrounding
- Thitu Island, Subi Reef
1.24 Loaita Bank
- Loaita Island, Lankiam Cay
1.25 & 1.26 Tizard Bank
- Namyit Island, Gaven Reefs, Sand Cay, Itu Aba Island, Petley Reef, Eldad Reef
1.26 West of Tizard Bank
- Western Reef, Discovery Great Reef, Discovery Small Reef

NE

Chart 93045 – approx. 10–12°N, 115–117°E;^[3]Sailing Directions pp10–11.^[1]

1.27 East of Loaita Bank
- Menzies Reef, Irving Reef, West York Island
1.27 Southampton Reefs (East of Tizard Bank)
- Hopps Reef, Livock Reef
Northern NE – Reed Bank
- Nares Bank, Marie Louise Bank
1.27 & 1.28 Central NE
- Jackson Atoll, Nanshan Island, Flat Island, Third Thomas Shoal, Hopkins Reef, Amy Douglas, Hirane Shoal, Hardy Reef
1.29 Eastern NE
- Sandy Shoal, Seahorse Shoal, Lord Auckland Shoal, Carnatic Shoal

SE

Chart 93046 – approx. 8–10°N, 115–117°E;^[6]Sailing Directions pp11–12.^[1]

1.30 & 1.31 Eastern SE
- Half Moon Shoal, Bombay Reef, Royal Captain Shoal
1.32 Central SE
- Sabina Shoal, Boxall Reef, Second Thomas Shoal
1.33 & 1.34 Western SE
- Mischief Reef, First Thomas Shoal, Alicia Annie Reef

SW

Chart 93047 – approx. 8–10°N, 113–115°E;^[7]Sailing Directions pp12–13.^[1]

1.34 & 1.35 Union Bank
- Johnson Reef, Collins Reef, Sin Cowe Island, Whitsun Reef, Grierson Reef, Lansdowne Reef,
1.36 Central SW
- Bittern Reef, Allison Reef, Cornwallis South Reef
1.37
- Pearson Reef, Pigeon Reef, Commodore Reef
1.38
- Investigator Shoal, Ardasier Reef, Ardasier Bank
1.39
- Erica Reef, Mariveles Reef, Dallas Reef, Barque Canada Reef.

Outside of Dangerous Ground

Sailing Directions pp13–15.^[1] Other parts of the Spratly Islands which are not inside Dangerous Ground include:

1.41 – 1.43 West of Dangerous Ground
- Fiery Cross Reef, London Reefs, Spratly Island
1.44 – 1.48 South West and South of Dangerous Ground
- Amboyna Cay, Southwest Bank, Rifleman Bank, Swallow Reef

Territorial disputes

The sovereignty of many of the islands is disputed, as are economic claims.

Notes

↑ Chart 93048 is not easily available on-line.

Related Research Articles

Loaita Island also known as Kota Island, with an area of 6.45 hectares -- is the tenth largest of the naturally-occurring Spratly Islands, and the fifth largest of the Philippine-occupied islands. It is located just to the west of the northern part of Dangerous Ground, and is 22 miles (35 km) southeast of Philippine-occupied Thitu Island (Pag-asa) and 22 miles (35 km) north-northeast of Taiwan-occupied Itu Aba Island.

Lankiam Cay, also known as Panata Island, is the smallest of the naturally occurring Spratly Islands. It has an area of 0.44 hectares, and is located about 7 nautical miles east-northeast of Philippine-occupied Loaita (Kota) Island, just west of the north of Dangerous Ground.

Sand Cay, also known as Bailan Island and Son Ca Island, is a cay on the north edge of the Tizard Bank of the Spratly Islands in the South China Sea. With an area of 7 hectares, it is the ninth largest, and the fourth largest former Vietnamese-administered, of the Spratly Islands. The island has been occupied by Vietnam since 1974,. It is also claimed by China (PRC), the Philippines, Vietnam, and Taiwan (ROC).

Amboyna Cay, also known as Vietnamese: Đảo An Bang; Malay: Pulau Amboyna Kecil; Datu Kalantiaw Island ; Mandarin Chinese: 安波沙洲; pinyin: Ānbō Shāzhōu, and other names, is an island of the Spratly Islands group in the South China Sea located just outside (SW) of the southwest of Dangerous Ground. It is SW of Barque Canada Reef, south of the London Reefs, and NW of Swallow Reef.

Erica Reef, also known as Enola Reef; Malay: Terumbu Siput, lit. 'Shell Reef'; Gabriela Silang Reef ; Vietnamese: đá Én Ca; Mandarin Chinese: 簸箕礁; pinyin: Bòji Jiāo, is located in the SW of Dangerous Ground, 24km east-northeast of Mariveles Reef in the Spratly Islands.

Mariveles Reef, is located in the SW of Dangerous Ground in the Spratly Islands. It is 59 kilometres (37 mi) slightly east of north from Swallow Reef and 35 nautical miles southeast of Barque Canada Reef.

Investigator Shoal, also known as Malay: Terumbu Peninjau; Pawikan Shoal ; Vietnamese: bãi Thám Hiểm; chữ Nôm: 𣺽探險; Mandarin Chinese: 榆亞暗沙/榆亚暗沙; pinyin: Yúyà ànshā, is located in the SW of Dangerous Ground in the Spratly Islands of the South China Sea.

Ardasier Reef, also known as Malay: Terumbu Ubi, lit. 'Yam Reef'; Antonio Luna Reef ; Vietnamese: đá Kiêu Ngựa; Mandarin Chinese: 光星仔礁; pinyin: Guāngxīngzǐ Jiāo, is a triangular shaped feature on the SW extremity of Dangerous Ground in the Spratly Islands.

Dallas Reef, also known as Malay: Terumbu Laya; Vietnamese: đá Suối Cát; Mandarin Chinese: 光星礁; pinyin: Guāngxīng Jiāo; Rajah Matanda Reef, lies on the SW extremity of Dangerous Ground in the Spratly Islands of the South China Sea.

Trường Sa is an island district of Khánh Hòa province in the South Central Coast region of Vietnam. It was established on the basis of the Spratly Islands, which is also claimed wholly or in part by Brunei, China, Malaysia, the Philippines and Taiwan. According to the 2009 census, the district has a population of 195 people.

The Tizard Bank, 10°15′N114°30′E is a partially sunken atoll and one of the significant maritime features of the north-western part of the Spratly Islands. It is claimed by Vietnam, China, and Taiwan, and various parts of it are occupied by these states.

Second Thomas Shoal, also known as Ayungin Shoal, Bãi Cỏ Mây (Vietnamese) and Rén'ài Jiāo, is a submerged reef in the Spratly Islands of the South China Sea, 105 nautical miles west of Palawan, Philippines. It is a disputed territory and claimed by multiple nations.

Bombay Castle, also known in Vietnamese: Đá Ba Kè; Mandarin Chinese: 蓬勃堡; pinyin: Péngbó Bǎo; Abad Santos Shoal, is a reef with a lighthouse in the Rifleman Bank of the southern Spratly Islands. It is occupied by Vietnam, but also claimed by China (PRC) and Taiwan (ROC).

North Danger Reef is one of the seven major reefs / banks / etc. in the Spratly Islands area of the South China Sea. It is the most North Western of the features of the Spratly Islands, located to the NW of Dangerous Ground.

The Loaita Bank is one of the significant maritime features in the Spratly Islands. It is about 20 nautical miles long on its NE-SW axis, and extends from Loaita Island to the NW of Dangerous Ground.

Third Thomas Shoal, known as Banko Thomas in the Philippines, Bãi Đồng Cam in Vietnam, and 和平暗沙 in China, is a reef in the north-west of the Spratly Islands in the South China Sea. It is located 7.5 nautical miles north of Flat island, and 73 nautical miles north of Mischief Reef.

Commodore Reef, also known as Rizal Reef, is a atoll located in the southeast of Dangerous Ground in the Spratly Islands in the South China Sea. It is located east of the Ardasier Reef and Investigator Shoal, 117.9 miles (189.7 km) NE of Swallow Reef and 167.1 miles (268.9 km) SE of Cuarteron Reef. The rock has been legally declared a rock.

Loaita Cay, also known as Melchora Aquino Island, is an island in the Spratly Islands. It has an area of 0.53 hectares and it's located about 5 nautical miles northwest of Philippine-occupied Loaita (Kota) Island, just west of the north of Dangerous Ground.

Loaita Nan is a shoal in the Loaita Bank of the Spratly Islands. Located at the southwest end of Daoming Reefs, it is composed of coral reefs. It is claimed by the government of China, Taiwan and the Philippines. Loaita Cay is northeast of Loaita Nan.

References

1 2 3 4 5 6 7 8 9 10 Sailing Directions (Enroute), Pub. 161: South China Sea and the Gulf of Thailand (PDF). Sailing Directions . United States National Geospatial-Intelligence Agency. 2017. p. 11-17.
1 2 3 http://www.oceangrafix.com/chart/zoom?chart=93044 Archived 2015-09-24 at the Wayback Machine NW Dangerous Ground
1 2 3 http://www.oceangrafix.com/chart/zoom?chart=93045 Archived 2015-09-24 at the Wayback Machine NE Dangerous Ground
↑ http://www.oceangrafix.com/chart/zoom?chart=93022 Archived 2019-06-17 at the Wayback Machine Western SCS
1 2 http://www.oceangrafix.com/chart/zoom?chart=92006 Archived 2015-09-24 at the Wayback Machine SE Spratlys, Brunei, North Borneo and Southern Philippines
1 2 http://www.oceangrafix.com/chart/zoom?chart=93046 Archived 2015-09-24 at the Wayback Machine Most of the SE of Dangerous Ground
1 2 http://www.oceangrafix.com/chart/zoom?chart=93047 Archived 2015-09-24 at the Wayback Machine SW Dangerous Ground