MANILA ( – The Philippine Coast Guard (PCG) has tracked the movements of China’s largest coast guard vessel, nicknamed “The Monster,” as it navigated through contested waters in the South China Sea over the past 10 days, officials said on Thursday.

Using Canada’s Dark Vessel Detection technology, the PCG monitored the Chinese Coast Guard (CCG) ship as it passed several Philippine-occupied features in the disputed Spratly Islands, raising concerns about China’s increasing maritime presence in the region.

The vessel, officially known as the CCG 5901, was observed near Parola Island, Pag-Asa Island, Zamora Reef, and Kagitingan Reef, all of which are claimed by the Philippines. It also approached Lawak Island, Patag Island, Escoda Shoal, and Bajo de Masinloc, according to PCG spokesperson Patrick de Jesus.

“The Monster” is the world’s largest coast guard vessel, measuring 165 meters in length and displacing 12,000 tonnes. Its presence in the contested waters has been viewed by some analysts as a demonstration of China’s growing maritime capabilities and assertiveness in the South China Sea.

As of Thursday morning, the PCG reported that the CCG vessel was last monitored 46 nautical miles southeast of Sanya, Hainan, China, apparently returning to its home port.

The tracking of the Chinese vessel comes amid ongoing tensions between Manila and Beijing over territorial disputes in the South China Sea. The Philippines has repeatedly protested China’s presence in what it considers its exclusive economic zone.

The use of Canada’s Dark Vessel Detection technology marks a significant development in the Philippines’ maritime surveillance capabilities. This advanced system allows for the tracking of vessels that may be attempting to conceal their locations or identities.

Philippine officials have not yet commented on whether they plan to file a diplomatic protest over the CCG vessel’s movements. The Chinese embassy in Manila was not immediately available for comment.

The incident underscores the complex geopolitical situation in the South China Sea, where multiple nations, including China, the Philippines, Vietnam, Malaysia, and Brunei, have overlapping territorial claims.