Okay folks, I'm gonna take a few moments to answer the #1 question I get asked every Winter--WHAT are you wearing on your feet?!?
I've accumulated many pairs of Winter boots over the years--good, bad (cold!), and ugly. When I'm heading out and know I'll be standing around in arctic conditions, there's one big, clunky, rubbery (and some say ugly) pair of clodhoppers that I always wear--my Bunny Boots!
WHAT ARE BUNNY BOOTS?
Bunny Boots, nicknamed by soliders after the puffy white feet of the snowshoe hare, are technically called Extreme Cold Vapor Barrier Boots-Type II. They were developed by the U.S. military during the Korean War and have been in military use ever since. The vapor barrier in the name refers to the boot's insulation being fully incased in rubber to prevent it from getting wet due to foot sweat. They're rated to -65F.
WHAT ABOUT THE BLACK BUNNY BOOTS?
There are no black Bunny Boots; however, Bunny Boots have a cousin called "Mickey Mouse Boots." Some people refer to either type as "Mouse Boots." The black boots have a resemblance to Mickey Mouse's jumbo cartoon kicks. The Mickeys are also awesome. They're rated to -20F and have a harder rubber. My first experience with vapor barrier boots was with the Mickeys. After years of cold feet, I got a pair of Mickeys. I used them for years bow hunting in Wisconsin and had warm feet happily ever after.
Why Bunny Boots?
Simply put: I've never had cold feet in them.
There are other types of Winter footwear that I might wear depending on the conditions and the activity, which I'll touch on below, but if it's subzero, and if I know I'm going to be stationary for long periods of time, Bunny Boots are my fail-safe plan.
The most extreme conditions I've worn my Bunny Boots were Winter camping in the Boundary Waters with ambient temperatures in the -20F to -40F range, while teaching at the Boy Scouts National Cold Weather Leader School. For this program, we are out for a few days camping on frozen lakes in quinzhees or trapper's trenches (types of snow shelters) without tent stoves. Other participants at the camp were wearing brand name, -100F rated pac boots, as well as different styles of mukluks, and quite a few were stamping around doing the cold foot dance. My toes stayed comfortably toasty. Did I mention that already? While it can get pretty cold in northern Minnesota, we have friends who worked on Alaska's North Slope and at McMurdo Station in Anatartica--places with real ice cold bragging rights--and both confirm that Bunny Boots are widely worn in those polar climates.
In addition to being dependably warm, the Bunnys are comparatively cheap! (Check your local military surplus shop, and I'm betting you'll find a pair in good condition at a reasonable price.)
ANATOMY OF THE BUNNY BOOT
What is it about the design of the Bunny Boot that makes it so warm?
Water conducts heat 25x faster than air. Protecting your boot's insulation from both internal (sweat) and external moisture retains the full heat trapping power of the Bunny Boot insulation. The thick layers of insulation and air are completely sealed inside and out in the boot's rubber. This seal prevents the felt from getting wet from external elements, foot sweat, or slush coming over the top of the boot--all of which would ruin the boot's insulative value.
If snow, water, or foot sweat has accumulated in the Bunny Boot, your foot will quickly warm it (however, the best course would be to drain the boot and switch into dry socks).
Bunny Boots also have unusually thick insulation (check out the cutaway photo). Bunny Boots have two layers of 1/2" thick felt under foot! You lose a lot of heat via conduction with frozen ground or ice in the deep cold, and this thick bottom layer really helps protect against that type of heat loss. (Tip: If you have enough room in your existing boots, adding an extra insole can increase your foot warmth. Just make sure your foot isn't squeezed into your boot and restricting movement after adding an insole.)
Roomy Toe Box
One of the reasons people get cold feet is their feet are crammed into their boots, restricting movement and blood flow. With Bunny Boots, people don't have that issue. Built with large roomy toe boxes that allow for plenty of wiggle room, Bunny Boots can easily accommodate feet even as large as mine. I wear size 15 shoes, but I have plenty of room in size 14 Bunny Boots (which is great because I had a long history of cold feet in tight boots that were never quite big enough).
Debunking the Bunny Boot Myths
As great as Bunny Boots are, there's quite a bit of misunderstanding surrounding them. For instance:
You need to blow in the valves. You don't; keep the valves sealed to prevent moisture from getting into the insulation. The purpose of the valves is attributed to the military: they used them during transport in unpressurized military cargo planes to keep the boots' sealed insulation chamber from blowing up.
You'll get trench foot. Trench foot is primarily an issue when your feet are subject to prolonged, cold, and wet conditions. Bunny Boots don't breathe and will have your feet swimming in sweat, but your feet will be warm. It's actually kind of amusing--and somewhat disturbing--to watch the vapor rise out of your boot and off your socks if you've had a hard, active day in them. Changing into dry socks and regularly airing and drying your feet will keep them in good shape. Some people use foot powder at night to combat the dampness, although I've heard from a physician that this is also not a good long-term practice. If I'm not moving much, I'll often leave the tops wide open. They're still plenty warm, but this helps to keep things aired out.
If my Bunny Boots "pop," they'll be worthless. I haven't had a puncture, but I'm not sure Bunny Boots would become totally worthless. You could seal the puncture with silicone sealant, a tire patch kit, duct tape, or maybe even pine pitch. Even with a puncture, Bunny Boots would still have as much, if not more, insulation as a regular pack boot.
Bunny Boots weigh a ton! Well, they're not ballet slippers, that's for sure; but, I think they're comfortable, especially for relatively stationary activities like nighttime in Winter camp, hunting, late-season Packer games, and ice fishing. For long-distance snowshoe treks, I'd choose mukluks or Tingley's, depending on the conditions. If I'm not traveling too far, I'll bring my Bunny Boots on the sled for evening wear and wear mukluks while I'm traveling. One particular issue with the Bunny Boots is that the rubber edge on the top of the boot can rub against your shins and calves. That rubbing has actually caused abrasions on my legs, like a rug burn, after on particularly hard slog in the boots. It helps to wear long socks, which you can pull up and fold down over the top edge of the boot to prevent chaffing. This can also help wick out a bit of the foot swampiness.
Are Bunny Boots the perfect boot?
No, they're probably not perfect. Even though I don't mind wearing them, others think they are big and clunky, and I'll admit they're not what I'd want to wear for long-distance skiing or snowshoeing. Your feet will sweat, and quite possibly smell really bad in them. And some who are more fashion conscious than I might be reluctant to wear them around town.
BUNNY BOOTS VS. OTHER WINTER BOOTS
So, when it comes right down to it, how do Bunny Boots compare to other Winter footwear?
Pac Boots The standard rubber-bottomed boot with a leather or fabric upper and removable liner, such as most Sorel models, can be a good all-around boot. Keys to performance with this boot are to make sure it's large enough to fit an extra insole (most have insufficient insulation underfoot and also lack the room to add a thick insole), a liner sock, and at least one thick wool sock. Thick felt insoles help with warmth, but mesh insoles can really help with sweat. Carrying an extra set of liners is a good idea with any boots where the liners are exposed. You can pull out the damp liners each night and dry them in your sleeping bag. Fun! Another helpful technique is to make your own vapor barrier by putting plastic bags over your liner socks (more fun!). This will keep your insulation dry.
Mukluks Mukluks are near perfect for "dry-cold" conditions. Dry-cold is when the outside temperature is consistently below 15F, so everything is frozen. True mukluks are intentionally not waterproof, so they breath well and allow your foot vapor to escape. They are also light, comfortable, and roomy enough to really let your piggies wiggle--all of which help with warmth. Mukluks are a poor choice in wet-cold conditions (above 15F) because they can get soaked from wet snow and slush. The soles of many mukluk designs also wear out fairly quickly. True native mukluks with hide bottoms may even wear out from walking on crusty snow, but their comfort makes it worth it! If you are standing around a campfire, that area might be slushy-- also not a good mix with mukluks. I've used both Steger Mukluks and Canadian MIlitary Surplus mukluks, and found both to be very comfortable. I almost always bring some type of wet-cold boot or overboot to complement my mukluks.
Neoprene Boots Neoprene boots, such as Muck Boots, have become very popular. They can be very warm, are easy to put on and take off, and are generally low maintenance. While they don't have a felt liner that can get wet, the lining of some neoprene boots does absorb foot moisture and isn't removable. I have a pair of Boggs rated to -40F in an obnoxious bright blue that I picked up for a song at a bargain basement outlet. While I love slipping them on to shovel snow, I haven't taken them Winter camping yet. My concern, especially if I'm camping in quinzhees without an external heat source to dry them, is that the foot moisture will freeze up in the boots overnight. Ben Piersma, of Ben's Backwoods, often wears Mucks, but said that he switched to muks (Mucks vs. mukluks!) when training with Mors Kochanski at -50C in Alberta for a week. He said another attendee wearing neoprene boots spent time each night trying to dry them out by the fire. I talked with a musher in Ely, MN who says he wears Muck boots all Winter and loves them, but admitted that he hasn't used them on an overnight trip.
Soft Shells with Liners There are various combinations of a soft waterproof shell with removable insulated liners that can be put together to make a wet-cold appropriate version of the mukluk. My favorite combination is using tall Tingley's overboots with insoles and liners. This soft, light, warm, and flexible system has been used by northern trappers and woodsmen for years. A more modern take widely used in the Ely area is Neos Overboots and liners. Many Winter backpackers and mountaineers will wear synthetic or down insulated booties inside shell boots in camp at night, and then wear ski or hiking boots while on the move during the day for a light, warm, and comfortable combo.
So, there probably is no one perfect Winter boot. Cold feet can ruin your trip though, so it's important to understand how your body creates warmth, as well as the uses and limitations of various boot systems. In my experience, Bunny Boots offer cheap, effective, multi-condition warmth, which is tough to beat.