In one unusual but revealing study, his researchers repeatedly immersed one side of people's bodies until it showed evidence of habituation, while keeping the other side warm -- and then turned them over and immersed the side that had never been in the cold water and found that there was still a significant reduction in their cold shock response.

CNN: Are polar bear plunges good for you?

As for squatters, who steal up to 15% of the nation's water: they may be in for a rude shock.

CNN: Special Report Drought

When people first immerse themselves in such frigid water, their bodies go into "cold shock, " and they start gasping for air, which puts a strain on the heart.

CNN: Are polar bear plunges good for you?

The Kyocera DuraPro is water, shock, dust, and vibration resistant and is encased in non-slip Dura-Grip material for a strong hold and extra durability.

ENGADGET: Kyocera DuraPro keeps the rugged flip phone alive on US Cellular for $100

The Seiko 5, as near as I can tell, got its start in the 1970s, and the name refers to its 5 attributes: water resistant, shock resistant, self-winding, day display, date display.

FORBES: Montre Sans Bull****: The Palate Cleansing Pleasure Of The Seiko 5

Their rough-hewn prototype sits in a small room at Trust Automation's headquarters in San Luis Obispo, California, using a water-filled vitamin bottle as a shock absorber. ("It runs like a Corvette on a Pinto engine, " Safreno says, smiling.) The ratty demo reel first shows a 22-second clip of an actor walking on a grassy lawn, past a blurred van, squirting water with a hose, at 24 fps.

FORBES: Film's Latest Picture Show

"The children screamed when the initial shock hit and when the adults dove in (to attempt rescue) they could feel the electricity in the water, " said Highway Patrol Sgt.

CNN: STORY HIGHLIGHTS

Tipton, who conducts research on the human body's physiological and psychological response to adverse environments, found that it takes as few as five immersions in icy water for the body to develop a tolerance that can reduce the risk of cold-shock response by half.

CNN: Are polar bear plunges good for you?