For one of the Championsheeps episodes we have been shooting some sheep synchronised swimming under water.
Obviously we can't actually shoot underwater, so the effect is created using lighting. Charles, The Director of photography, and Clive, a spark, placed a light diffusion filter between the camera and the set, which created a murky, underwater look.
Then they positioned a motorised spiral of metal wire in front of a light to create an underwater ripple effect. These pictures show the difference the filter made, and the metal spiral used for the ripple effect.