Snorkel crews endure nature's cold plunge

Recent health and wellness science implies that a “cold plunge” may be good for the human brain, body and bragging rights. But why spend money on a kiddie pool and 40 pounds of ice when you can spend it on another fly rod and an elk tag?

Idaho is chock-full of natural cold plunges. Just ask your regional Idaho Fish and Game snorkel crew. Our four crews (based out of Nampa, McCall, Salmon and Lewiston) spend their summer constantly alternating between hot, sweaty hikes and bone-chilling snorkel surveys.

This year, the Nampa research snorkel crew completed “extensive” surveys in both Clearwater and Salmon River basins. These survey locations are randomly selected in a manner that distributes sites “evenly” across all streams within a selected basin. This is done to create a spatially-balanced data set that represents the basin and its individual waterbodies as a whole. Because of this, a crew may be sampling a headwater tributary one day and a mainstem river the next. 

As the Idaho mountains would have it, headwater tributaries are fueled by snowmelt at higher elevations, providing our lowest survey temperatures at ~6 degrees Celcius (42.8 degrees Fahrenheit). As that water moves down the landscape, warmer air temperatures, less canopy cover, exposure to sunlight and an occasional hot spring cause water temps to rise. This creates a relatively more comfortable snorkel environment in temperatures ≥ 10 degrees Celcius (50 degrees Fahrenheit) lower in the basin. 

Preliminary health and wellness studies report that an effective cold plunge may be completed at temperatures ≤ 15 degrees Celcius (59 degrees Fahrenheit) for at least 15 minutes per week, with submersion up to the neck. An average snorkel survey takes about 45 minutes and includes partial submersion of the entire body, including the neck, face and head.

**Disclaimer: Whether in a kiddie pool or an Idaho tributary, cold plunges are taken at one’s own risk. Most snorkelers don a fashionable wet suit, gloves and hood made of 5-plus millimeters of neoprene. This, however, does not keep whitewater from penetrating holes worn in through the fingertips, knees and elbows during a typical season of underwater rock climbing.

The average temperatures for each subbasin (and corresponding drainage) surveyed by our 2023 Nampa crew are as follows:

While us humans spend ample time and money on collecting the best gear to keep us warm and dry, our salmonid counterparts soak in these “cold plunges” in comfort. Some of our favorite slippery friends — think Chinook, steelhead, and cutthroat — require water temps less than or equal to 10 degrees Celcius (50 degrees Fahrenheit) for egg incubation and hatching, and temps less than or equal to 15 degrees Celcius (59 degrees Fahrenheit) for optimal juvenile growth. In humbling comparison, most humans prefer between 20-22 degrees Celcius (68-72 degrees Fahrenheit) whilst “plunging” into our couch.

Moral of the story? Fish are hardcore, and nature provides free therapy for those who wish to explore it.