The MT Castillo de Bellver oil spill began on 6 August 1983, when the Spanish tanker caught on fire off Saldanha Bay, approximately 70 miles northwest of Cape Town, South Africa.

It was carrying 250,000 tonnes (300,000 cubic metres) of light crude oil, and was traveling through an environmentally sensitive area known for its seabird rookeries and important commercial fishing grounds.

The crew abandoned the ship, which proceeded to drift off the coast, eventually breaking in two at around 10 a.m.[11][12] Approximately 50,000–60,000 t (110,000,000–130,000,000 lb) of light crude was initially spilled into the sea, creating a flaming oil slick.

[11] The stern section of the ship capsized and sank on 7 August in deep waters, 36 km (22 mi) off the coast.

[4] The bow had drifted towards an area that included the Langebaan Lagoon marine life sanctuary, a 15-mile (24 km)-long strip of coast south of Saldanha Port.

[13] Weather conditions proved to be conducive to spill response and helped prevent a major onshore environmental disaster.

[16][13] "Black rain" of oil droplets fell immediately to the east of the spill during the first 24 hours on wheat-growing and sheep-grazing fields, but no long-term damage was recorded.

[8] According to tests conducted on sediment and water samples and plankton trawls, no abnormal presence of hydrocarbons was detected.