This is a single exposure, handheld, in-camera ICM, using a very fast, sort of wavy and twisting motion. General post-processing edits in Lightroom, with spot removal in Photoshop.
Canon 5D Mark III, Canon f/4L 24-105mm Lens
ISO 100, 24mm, f/5.6, 1/2 second
NiSi 10-stop ND filter