[3][note 1] The city, constructed in a lagoon, consists of a series of small artificial islands linked by a network of canals.

[14] Nan Madol was the ceremonial and political seat of the Saudeleur Dynasty, which united Pohnpei's estimated population of 25,000 people until about 1628.

[15] According to Pohnpeian legend, Nan Madol was constructed by twin sorcerers Olisihpa and Olosohpa from the mythical Western Katau, or Kanamwayso.

The brothers arrived in a large canoe seeking a place to build an altar so that they could worship Nahnisohn Sahpw, the god of agriculture.

Olosohpa married a local woman and sired twelve generations, producing sixteen other Saudeleur rulers of the Dipwilap ("Great") clan.

Nan Madol served, in part, as a way for the ruling Saudeleur chiefs to organize and control potential rivals by requiring them to live in the city rather than in their home districts, where their activities were difficult to monitor.

to have caused them eventually to abandon Nan Madol and move back to their own districts, although there are other explanations for the desertion of the complex, such as a sharp population decline.

Today Nan Madol forms an archaeological district covering more than 18 square kilometres (6.9 sq mi) and includes the stone architecture built up on a coral reef flat along the shore of Temwen Island, several other artificial islets, and the adjacent Pohnpei main island coastline.

Carbon dating indicates that megalithic construction at Nan Madol began around AD 1180 when large basalt stones were taken from a volcanic plug on the opposite side of Pohnpei.

[23][24] In 2013, Ishimura and others used multi-beam sonar, ROVs, and scuba diving to examine submerged block-shaped features and columnar objects and the blue hole.

They also concluded that the blue hole is a sinkhole that developed in reef limestones during sea level lowstands of glacial maximums.

[26][27][28] Nan Madol was featured in episode two of the pseudoarchaeological work Ancient Apocalypse by Graham Hancock which aired on Netflix, in which false claims were made about the age of the site.

Experts in Pacific geography and archaeology have characterised Hancock's claims about Nan Madol as "incredibly insulting to the ancestors of the Pohnpeian [islanders] that did create these structures", linking them to 19th century "racist" and "white supremacist" ideologies.