From the Open Water Swimming Dictionary:

Wave Shark” (noun) is a wave that appears like a shark to open water swimmers and their coaches and support crew. It is simply a wave in the ocean, but its form or splash temporarily leads swimmers, coaches and crew to think there is a shark in close proximity.

The coach was startled when she thought she saw a wave shark in the water near her swimmer.

Photo of Marcos Díaz along the northern coast of the Dominican Republic.

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