A foaming whitewater wave that first moves into deep water, so that it reverts back to an unbroken swell—or the whitewater is reduced to a fringe along the crest—then onto a shallow area where the wave once again steepens and breaks.

Reforms come in all sizes and shapes. Waves at Second Reef Pipeline in Hawaii will reform into a gaping tube on the nearshore reef; waves at Huntington Beach, California, usually reform into a boring shorebreak closeout.