The third helmet bobbed.
Sylvia nodded, and her helmet bobbed.
The helmet bobbed in a nod.
The officer's broad helmet bobbed as he shouted.
Guy had been thrown overboard by the impact of the first wave, and his red helmet bobbed by as he was swept downriver.
Soon afterward the yellow helmet bobbed to the surface, floated into an eddy and was beached on a gravel strip fifty yards downstream.
His helmet bobbed on his head and was heavier than he had expected.
Directly in front of him, the other scout's helmet bobbed abruptly into view with a hissing rush of sand.
The helmet of his suit bobbed forgotten against one wall.
Reed's helmet bobbed as he nodded.