Peculiar wave in surf zone?

On a trip to New Zealand we observed a curious wave phenomenon. The beach was extremely shallow and broad. When water retreated from the beach and encountered the incoming swell, an interference phenomenon created a wave that traveled at pretty high speed in a direction parallel to the beach. The width of the wave in the direction perpendicular to its direction of travel, was very small. The waves persisted for distances of several hundred yards before collapsing.

Any idea what this type of wave is called?
 
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