A great video shows South Korean archaeologists discovering a heavy slipway used for Chinese merchant ships about 900 years ago, along with an abundance of ancient coins and ceramic artifacts.
The discovery took place during South Korea’s underwater archaeological surveys off the coast of Sinchangli on Jeju Island between May and July this year.
Footage shows divers tying ropes to a large rock so that it can be pulled back to the surface.
A closer look at the scattered treasure reveals that bright objects and scraps of crockery are collected on the seabed and carefully put in baskets by the divers.
The stone ramp, also called a boat ramp, was 3.1 meters long and weighed 586 kilograms.
According to the National Institute of Maritime Cultural Properties of South Korea and the National Jeju Museum, both of which took part in the investigation, the large stone was broken in two when they found it.
The stone body is a diamond, thick in the center and tapering on the left and right sides.
There is a 22 centimeter (8.6 inch) slot in the center and a 7 centimeter (2.8 inch) slot for attaching anchor pins.
Boat ramps like this one were popular in China during the Song and Yuan dynasties, according to the study.
In addition, experts also discovered coins and ceramics from the Northern Song Dynasty, which began in AD 960 and lasted until 1279.
The discovery indicates that Jeju Province once held an important position in East Asian maritime trade.