The New Hampshire Fish and Game Department is warning people not to join in a current trend where teenagers dare each other to jump into frigid waters.
The department says the "Polar Plunge" is being fanned on social media; teens are dared to jump into the freezing water wearing only summer swimwear and without life vests. They also have to dare five others to take the plunge.
The state's lakes are still dangerously cold and rivers are swollen with snowmelt, full of debris and fast-moving.
The department says the icy waters can quickly debilitate even good swimmers and there is a real danger of hypothermia.