Guishan Island, formerly known as Trashima Island, was renamed Guishan Island to commemorate the People's Liberation Army martyrs who died in the battle to liberate Wanshan Islands aboard the ship "Guishan".

Guishan Island is located in the district of Guishan Town, Zhuhai City, and is the seat of Guishan Town government. The town area is composed of 22 islands and surrounding 800 square kilometers of sea area, of which Guishan Island and central island, Niutou Island with levees to form a land area of nearly 6.92 square kilometers of the core island group.

Guishan Island is located in the golden position between Hong Kong, Shenzhen, Macao and Zhuhai, about 17 nautical miles from Macao and Xiangzhou in the west, and only 3 nautical miles from Lantau Island in Hong Kong in the north. The surrounding waters have many bustling waterways such as Daxi and Dahao running through it, and the famous Pearl River Estuary international anchorage is located in it, known as "Wanshan Fortress".