In which year was Dordrecht Deep discovered?

Dordrecht Deep was discovered in 1960.

The discovery was reported during Australian oceanographic work in the Indian Ocean. A follow-up survey in 1961 by the Australian research vessel HMAS Diamantina confirmed the bathymetry and investigated the surrounding seafloor. The deep and the larger Diamantina fracture zone ultimately took their names from that vessel.

The name reaches further back into maritime history. Dordrecht was a ship of the Dutch East India Company that explored the western Australian coast in 1619 and discovered the Houtman Abrolhos. That historical connection explains why a feature far offshore carries a Dutch-derived name.

The 1960 date can be confused with later, more precise surveys. Modern mapping has revised the estimated depth substantially: the Five Deeps Expedition measured Dordrecht Deep at roughly 7,019 metres, shallower than older figures. That changed its standing relative to the Sunda Trench, but not the year of its original discovery.