'Reef of Mabini'),[1][2] is a reef in the southwest portion of the Union Banks in the Spratly Islands of the South China Sea.

It is controlled by the People's Republic of China (PRC), but its ownership is disputed and also claimed by the Philippines, Taiwan (ROC), and Vietnam.

Prior to 2014 it housed a number of small buildings, wharves and a fortified Chinese maritime observation station.

[7] During 2014, Chinese reclamation work expanded the usable surface area to 10.9 hectares (27 acres), accommodating what appears to be a military and radar base and a small harbour.

[8] In late 2016, photographs emerged which suggested that the expanded reef has been armed with anti-aircraft guns and a CIWS missile-defence system.