Philippines Questions China's Blue-Hole Claim at Bajo de Masinloc

Article by A. Agott

Published on July 1, 2026 06:30AM

The Philippines challenges China's claim over the mysterious blue-hole at Bajo de Masinloc, amidst escalating maritime tensions.

China’s latest claim on blue-hole announcement at Bajo de Masinloc (Scarborough Shoal) looks less like a neutral scientific milestone and more like another layer in a long-running sovereignty dispute over the West Philippine Sea. For the Philippines, the sharper story is not the coral sinkhole itself, but how Beijing keeps pairing research language on Bajo de Masinloc and regards the region as part of its maritime domain. ¹

What China is saying

Chinese state-linked reporting says researchers found a rare coral reef blue hole inside the lagoon at Bajo de Masinloc (Internationally known as Scarborough Shoal or what Beijing calls as Huangyan Dao), and that it may be about 3,200 years old. Those reports also say the feature sits within a rich marine ecosystem, with coral and fish diversity that Chinese scientists are presenting as evidence of environmental and geological value. ¹ ² ³ ⁶

Why Manila is alarmed

The timing matters because China has also been using patrols, floating structures, and other activities around the shoal to reinforce its presence there. Recent mainstream coverage has described Beijing’s actions near Bajo de Masinloc as part of a broader effort to strengthen control over disputed waters, while Philippine authorities have monitored separately documented Chinese structures inside the lagoon. ⁴

The Philippine frame

From the Philippines' perspective, the discovery will be used by Beijing to normalize Chinese administrative language over a contested area that is far closer to Luzon than to Hainan, and that remains a flashpoint in Manila–Beijing relations. ¹ ⁵

A more balanced read

A fair reading is that the blue hole may indeed be a legitimate marine discovery worth scientific study, but its political packaging is hard to ignore. In the South China Sea, even environmental research can become part of a sovereignty narrative, especially when it is tied to the West Philippine Sea and published alongside narrative messaging as jurisdiction and control. ¹

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Notes:

¹ South China Morning Post, “China discovers rare coral reef blue hole in disputed Scarborough Shoal”.

² Associated Press-style regional coverage via Anadolu Agency, “China discovers its 1st coral reef blue hole at Huangyan Dao in disputed South China Sea”.

³ Radio Free Asia, “Turtle power: how China uses scientific research to try to bolster territorial claims”.

⁴ CBS/other mainstream regional reporting indexed in search results on Scarborough-related patrols and structures.

⁵ Manila Bulletin, “How vigilant PH gov't agencies discovered China's 'movable floating platform' in Bajo de Masinloc”.

⁶ South China Morning Post, June 29 report on Chinese vessels shadowing US-Philippine drills near the shoal.⁩