A maritime advocacy group on Thursday raised concerns over the 21-day presence of a Chinese marine research vessel inside Bajo de Masinloc, or Panatag Shoal, questioning what the vessel was studying and how the information gathered could be used.

Dr. Jose Antonio Goitia, chairman emeritus of Alyansa ng Bantay sa Kapayapaan at Demokrasya, said the Haiyang Dizhi Shi Hao, operated by China’s Guangzhou Marine Geological Survey, stayed inside the shoal from 11 August to 1 September.

Goitia said the vessel is designed for geological survey work and can examine the seabed and shallow subsurface.

“A 21-day stay inside the shoal warrants scrutiny, regardless of its stated purpose,” he said.

Goitia linked the vessel’s presence to broader concerns over China’s activities in the West Philippine Sea, citing developments at Panganiban Reef, or Mischief Reef, where Chinese structures first appeared in 1995 and were later expanded.

“The temporary presence of today can become the accepted reality of tomorrow if it is allowed to continue unchecked,” Goitia said.

He also cited a floating platform or raft spotted inside Panatag Shoal in May, which he said was reportedly linked to Chinese research vessels.

“Any single incident might have an explanation. A pattern is harder to wave away,” he said.

Goitia said the issue was not simply whether China was conducting research, but what information was being gathered and what it could eventually support.

“Sovereignty is rarely lost all at once. It is gradually eroded when challenges to it are repeatedly allowed to pass unanswered,” he said.

He added that activities capable of changing the status quo at Panatag Shoal should be closely monitored while they are ongoing.

“Our sovereignty cannot be traded, surrendered, or made a subject of negotiation. Panganiban was a warning the Philippines read too late. Panatag is the chance to read it on time,” Goitia said.