One possible source is the wreck of SS Mira, a British oil tanker that hit a mine almost 100 years ago during the first world war. It went down in almost exactly the same spot where a possible plume was picked up in satellite imagery five miles (8km) off Birling Gap just hours before Sunday’s incident. Neodaas, a facility of the UK Natural Environment Research Council that works with the Plymouth Marine Laboratory, published images of the possible plume picked up that morning. This is what can be seen in the water – the plume is moving in the right direction for the tidal current. Sussex police said a ship in the Channel was still considered the most likely source of the mystery plume.

Source: The Guardian September 01, 2017 18:47 UTC