The Abyss Record

East of the Eastern Sea, unknown tens of thousands of miles away, lies a great chasm with no bottom, called Guixu. In October of the lunar calendar in 1076 AD, a dull rumble sounded at the bottom of the Bashi Strait, causing tidal waters to surge inland, destroying homes and drowning residents in the counties of Haiyang and Chaoyang in Guangdong, and wiping out flora and fauna on Dong Island in the Xisha archipelago. The Song history merely noted a brief phrase "sea tide overflowed," but no one knew that on the same night, a fleet departing from Mingzhou Harbor, carrying the secret "underwater city" blueprints of the Southern Song court, along with over three hundred souls aboard, was swallowed whole by Guixu. Eight hundred years later, a deep-sea probe at a depth of 1600 meters on the South China Sea seabed encountered a rotting whale. — Description from novelcodex.org