North Danger Reef, ft. Southwest Cay, Northeast Cay, Spratly Islands
Updated August 26, 2024
North Danger Reef
North Danger Reef has both Vietnamese and Philippine islands and is located north of Subi Reef and Thitu Island. It is just west of Trident Shoal (an uninhabited, underwater, natural reef shoal). This is a large atoll, a shoal and a reef structure with at least four land formations above water. It contains two permanently inhabited and developed islands: Southwest Cay and Northeast Cay.
Northeast Cay, Philippine, is a largely grass covered island with about a dozen buildings, a helipad, and the Parola Lighthouse. Northeast Cay is mostly green with maybe a dozen buildings, an athletic court, a helipad, and is Philippine.
Southwest Cay, or Dao Song Tu Tay, Vietnam, has the yellow star on the roof of a building. It has a large protected bay and boat launch facilities. It appears to have significant island defensive fortifications.
The new South Reef, Vietnam, will dwarf them all in size and scope. The South Reef had new development and infrastructure in satellite imagery dated 6/25/2019. In 2019, this was a new sandy outcropping and the two-part, connected reclamation infrastructure. In this case, we see five boats in the satellite photo. location: 11°23'29"N 114°18’13"E. Now, it is a full fledged island development, as seen in Copernicus Browser Sentinel-2 imagery 7/31/2024. The new South Reef is in a strategic location, 32.9 km from Thitu Island (Pag-Asa or Kalayaan) which is Philippine's primary island in the Spratlys, and 52.6 km from Subi Reef, which is one of three of China's primary islands in the Spratly Islands.
In summary, Vietnam is building a new island and the rest of the islands appear 'status quo' for the past few years.
North Danger Reef
North Danger Reef has both Vietnamese and Philippine islands and is located north of Subi Reef and Thitu Island. It is just west of Trident Shoal (an uninhabited, underwater, natural reef shoal). This is a large atoll, a shoal and a reef structure with at least four land formations above water. It contains two permanently inhabited and developed islands: Southwest Cay and Northeast Cay.
Northeast Cay, Philippine, is a largely grass covered island with about a dozen buildings, a helipad, and the Parola Lighthouse. Northeast Cay is mostly green with maybe a dozen buildings, an athletic court, a helipad, and is Philippine.
Southwest Cay, or Dao Song Tu Tay, Vietnam, has the yellow star on the roof of a building. It has a large protected bay and boat launch facilities. It appears to have significant island defensive fortifications.
The new South Reef, Vietnam, will dwarf them all in size and scope. The South Reef had new development and infrastructure in satellite imagery dated 6/25/2019. In 2019, this was a new sandy outcropping and the two-part, connected reclamation infrastructure. In this case, we see five boats in the satellite photo. location: 11°23'29"N 114°18’13"E. Now, it is a full fledged island development, as seen in Copernicus Browser Sentinel-2 imagery 7/31/2024. The new South Reef is in a strategic location, 32.9 km from Thitu Island (Pag-Asa or Kalayaan) which is Philippine's primary island in the Spratlys, and 52.6 km from Subi Reef, which is one of three of China's primary islands in the Spratly Islands.
In summary, Vietnam is building a new island and the rest of the islands appear 'status quo' for the past few years.
There is also a brand new third island in this neighborhood. It is under significant reclamation, at location Lat: 11.373580, Lng: 114.304730, in Copernicus Browser Sentinel-2 L2A imagery from 7/31.2024.
We cannot wait for this island to show up in Google Earth, so we can take a closer look around (their satellite imagery is higher resolution for our account).
We cannot wait for this island to show up in Google Earth, so we can take a closer look around (their satellite imagery is higher resolution for our account).
New South Reef, North Danger Reef, Google Earth 2019 - reclamation infrastructure and five boats
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New South Reef, North Danger Reef, Google Earth 2019 - reclamation sand spit
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New South Reef, Sentinel-2 L2A, Copernicus Browser eESA, 7/31/2024. There are 15 ships and a massive reclamation effort underway.
Moving north to Southwest Cay, this formerly primary island in the reef has a protected bay, two radomes (radar domes), and finished, new buildings around the island. We see significant defensive infrastructures dug into the perimeter of the island (like a trench network), especially around the Western approaches. We see a large fixed-cannon emplacement on the northeast side in front of a large building, protecting the bay and the yellow-star building. There is a large parade ground and helicopter pad in the middle of the island. We see a large protected bay with a 'roll on, roll off' building connected by a ramp to the bay, and one dock with a ship currently docked.
However, we cannot see much of the southern side of the island due to cloud cover. Satellite Imagery: 11/30/2023. Location: 11°25'41"N 114°20'04"E. This island measures 0.40 miles in diameter.
North Danger Reef, Southwest Cay, is also named Song Tu Tay in the Copernicus Browser.
However, we cannot see much of the southern side of the island due to cloud cover. Satellite Imagery: 11/30/2023. Location: 11°25'41"N 114°20'04"E. This island measures 0.40 miles in diameter.
North Danger Reef, Southwest Cay, is also named Song Tu Tay in the Copernicus Browser.
North Danger Reef, Southeast Cay, Google Earth 11/30/2023
This picture of the Eastern coast of the island has two elevated balls in close proximity, but with different shapes. One sits atop a rectangular white base, and the other is more cylindrical. the cylindrical one has two additional, identical 'bases' right behind it.
It might make sense that one is a radome and the other is a water tower to store fresh water. Fresh water is difficult to come by on an island (If there are no freshwater wells, water must be transported in, desalinated, or caught as rainwater. We note the two fixed gun emplacements near the sea-wall.
It might make sense that one is a radome and the other is a water tower to store fresh water. Fresh water is difficult to come by on an island (If there are no freshwater wells, water must be transported in, desalinated, or caught as rainwater. We note the two fixed gun emplacements near the sea-wall.
Southwest Cay, Island Detail East, Google Earth, 11/30/2023
The island has a roll-on, roll-off boat launch under a roof with a yellow star. This is a design we have seen on another Vietnamese island. Notice the two fixed gun emplacements near the building facing out to sea.
Southwest Cay, Island Detail North, Google Earth, 11/30/2023.
Northeast Cay is more of a tropical island with a few buildings, a basketball court, and a dirt path to the center of the island where we see what looks like an anti-aircraft and radar installation. The island is 0.49 miles in length. We see no airport, no finished port facilities, and the roads are more like trails. We do see a helipad. Location: 11°27'10"N 114°21'25"E. Google Earth satellite imagery dated 4/23/2023.
Northeast Cay, Full Island. Google Earth 4/23/2023.
Continuing east to the extreme north of the atoll, we see a new construction sandy outpost. Location: 1°27'39"N 114°23’28”E. This satellite image was taken 03/07/2021. We confirm that as of 7/31/2024, this reef still has the same sandy spit according to Sentinel-2 L2A imagery. This does not show up on Maxar Xpress.
Extreme northeast of North Danger Reef contains a sandy spit, Google Earth 03/07/2021
Trident Shoal
Due east of North Danger Reef is Trident Shoal, at location 11°27'07"N 114°40'59"E, which is an adjacent 25.5 km coral atoll pair that is completely submerged and undeveloped. Sentinel-2 satellite imagery 7/31/2024. With less cloud cover, here is an image from 5/22/2024.
Due east of North Danger Reef is Trident Shoal, at location 11°27'07"N 114°40'59"E, which is an adjacent 25.5 km coral atoll pair that is completely submerged and undeveloped. Sentinel-2 satellite imagery 7/31/2024. With less cloud cover, here is an image from 5/22/2024.
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Area
Name 1
Nearest Land
Distance from Land (miles)
Location (latitude & longitude)
Diameter (miles)
Date of Satellite Imagery
Airport Present?
Helipad Present?
Port / Dock Facility Present?
Buildings Present?
Defensive Infrastructure Present?
Athletic Facilities Present?
Hospital Present?
Sand Only Island?
Dredging Infrastructure Only?
Spratly Islands
North Danger Reef (4 islands)
Philippines and Vietnam
340 and 344
11°27'09"N 114°21’16”E.
0.34
3/7/2021
No
Yes
Yes
Yes
No
No
No
Two are sand only
One is infrastructure only
Name 1
Nearest Land
Distance from Land (miles)
Location (latitude & longitude)
Diameter (miles)
Date of Satellite Imagery
Airport Present?
Helipad Present?
Port / Dock Facility Present?
Buildings Present?
Defensive Infrastructure Present?
Athletic Facilities Present?
Hospital Present?
Sand Only Island?
Dredging Infrastructure Only?
Spratly Islands
North Danger Reef (4 islands)
Philippines and Vietnam
340 and 344
11°27'09"N 114°21’16”E.
0.34
3/7/2021
No
Yes
Yes
Yes
No
No
No
Two are sand only
One is infrastructure only
Trident Shoal and Lys Shoal, found east of the North Danger Atoll, are fully submerged as of 12/14/2025, look fully submerged. Location: 11°27'17"N 114°40'36"E.
