In the summer of 1916, thousands flocked to the New Jersey shore to seek relief from the polio epidemic and severe heat wave plaguing the northeastern US. As WWI raged in Europe, the vacationers watched for German U-boats that were reportedly maneuvering off the coast, but they were unaware of a different danger lurking(潜む)beneath the water's surface - sharks. Between July 1 and July 12, sharks attacked 5 people along the Jersey coast, killing 4.