These two platforms sit offshore from the two nuclear power stations in Sizewell, Suffolk. Sizewell A is decommissioned but Sizewell B is active, and a Sizewell C is planned. The platforms service the intake and discharge tunnels used to run sea water through the cooling system. The outflow pipe created an area of warm water that was popular with swimmers, who would gather under the nearer outflow platform at low tide.
This was taken during daylight using a ten-stop ND filter to get a 30s exposure time.
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