The Sanchi oil tanker collision occurred on 6 January 2018 when the Panamanian-flagged, Iranian-owned tanker Sanchi, with a full natural-gas condensate cargo of 136,000 tonnes (960,000 barrels), sailing from Iran to South Korea, collided with the Hong Kong-flagged cargo ship CF Crystal 160 nautical miles (300 km) off Shanghai, China.

[7] The other ship involved in the collision, CF Crystal, was a bulk carrier on a voyage from Kalama, Washington, U.S., to Machong, Guangdong Province, China, with 64,000 tonnes (71,000 short tons) of grain.

[10] The South Korea Maritime Police Agency and the United States Navy assisted Chinese authorities in firefighting and the search for the missing crew of Sanchi, which continued despite the risk of the tanker exploding.

"[14] On 13 January, a Chinese rescue team recovered two bodies from a lifeboat aboard Sanchi and salvaged the voyage data recorder from the bridge.

The four-person salvage team, although equipped with respirators, were forced off the vessel less than half an hour after boarding because the wind had shifted and toxic smoke had complicated the operation.

[19] According to a report by Reuters,[20] because of the incident, a slick 13 by 11 kilometres (7.0 by 5.9 nmi) in size was formed on the sea surface, which is being pushed toward Japan by wind, and efforts to contain it were begun by ships surrounding the spill.

[24] Using updated simulations based on the sinking location of Sanchi, the same researchers subsequently estimated that contamination could reach Japan within one month, due to the close proximity of the strong Kuroshio Current.

A report by Nature stated that because of this difference, perhaps the more important aspect of this spill is the immediate toxic effect of it on the marine inhabitants, with less concern about deposition of condensate on sediments or polluting beaches.