A building on the sea called Johnson South Reef or Chigua Reef is a reef in the Spratly Islands in the South China Sea. It is contiguous with Vietnam-occupied Collins Reef which lies 4 miles (6 km) away northwest. Naturally above water only at low tide, but some sources say that many rocks are above water at high tide. This is the site of Johnson South Reef Skirmish in 1988, fought by China and Vietnam which resulted to more than 70 Vietnamese deaths.
This reef is also being claimed by the Philippines and Vietnam.