The surfer, standing in the tube, or just in front of the break, slides down the wave like a skier, while the wave, and the buoyancy of the surfboard, bear him upwards and forwards.

ECONOMIST: On the beach

Second, they have shed light on something else originally studied by Dr Walker: the optimal speed of the break across the face of the wave.

ECONOMIST: On the beach

Because a surfer stays just ahead of the break, a wave that breaks very slowly carries him straight towards shore at only the speed of the wave.

ECONOMIST: On the beach

The weekly chart shows that FXE formed a continuation pattern early in 2012, as the break of support (line b) signaled another wave of selling.

FORBES: 3 ETF Currency Plays

After the wave's shape, the speed of the break is the most important factor in good surf.

ECONOMIST: On the beach

Wave breakpoint: the point where the waves break.

UNESCO: L O S S A R Y

On top of which, a state-mandated break-up could trigger a wave of lawsuits, further eroding trust in the system.

ECONOMIST: Bond insurers and the markets