Tizard Bank, Atoll in the Spratly Islands, South China Sea

Tizard Bank is a partially sunken atoll in the Spratly Islands, 59.36 km long and up to 21.04 km wide, with a total area of 953 km². Its central lagoon is generally 10 to 40 m deep, reaching 80 m at its greatest depth, and holds coral heads as shallow as 6 m. The reef rim rises steeply from surrounding depths of 500 to 700 m and carries islands, cays, reefs and shoals, including Itu Aba Island on the northwest edge and Namyit Island on the south side.

British oceanographer Thomas Henry Tizard surveyed and mapped this marine formation in the 1860s while aboard the HMS Rifleman. His explorations provided the first detailed knowledge of the area and gave it its lasting name.

The bank's Chinese name, Zheng He Qunjiao, adopted in 1947, honours the Ming admiral Zheng He, though no evidence shows he ever visited. Fishermen from Hainan used the islands before the 1870s, and Itu Aba held a semi-permanent Chinese fishing settlement.

Navigation here demands careful attention because of numerous shallow areas and underwater obstacles throughout the formation. Anyone planning to visit or operate in this area should work with specialists familiar with local marine conditions.

The bank's name honours Thomas Henry Tizard, the British oceanographer who surveyed it from HMS Rifleman in the 1860s; in 1947 the Republic of China renamed it Zheng He Archipelago after the Ming admiral, though no evidence shows he ever reached it.