Slot canyons, including Zion Narrows, are deceptively cold—and often wet. The temperature in the sun may be 100 degrees, but expect it to drop as much as 30 degrees when you drop into the shade. At the bottom, the rock walls get little direct sun, so they radiate cold. Add water—many slots have wading and even swimming sections—and convective afternoon winds, and you have a recipe for hypothermia. Not all slot-canyon hikes are that risky, of course, but the point is to call ahead about conditions and come prepared for the worst. For spring through fall, that means packing the following.
1. Footwear: Your feet will get wet when canyoneering, no matter what shoes you wear. When you're wading through creek bottoms all day, it's just unavoidable. So avoid the waterproof boots-which won't drain-and go for lightweight shoes or sandals with sticky rubber outsoles. Many canyon veterans simply wear sport sandals or even sneakers; both do the job quite well, especially when paired with waterproof socks (a good idea if the water is cold). A more performance-oriented option is Five-Ten's Canyoneer 2, and over-the-ankle boot with a fast-draining mesh upper, snug neoprene ankle protection, and superior traction.
2. Baselayers: When the temperature drops or the wind kicks up, it's good to have warm baselayers in your pack for immediate next-to-skin insulation. Wool has been making a comeback among outdoor aficionados, in large part because it's gotten a lot softer and less itchy. MontBell's Super Merino tops and bottoms excelled in BACKPACKER's last major apparel review. Read about these and other long johns here.
3. Hat and Gloves: Any warm fleece or wool hat will do, but BACKPACKER editors like the sun/wind/warmth versatility of Outdoor Research's Prismatic Cap, a windproof baseball hat with a microfleece lining and removable ear flaps. For your hands, they love Kombi's Windbreaker Fleece glove, a workhorse with good grip. If you'll encounter lots of water or temperatures below 50 F, consider investing in a pair of waterproof neoprene gloves (like the kind worn by SCUBA divers).
4. Jacket:For conditions where you might need instant warmth but might get wet, too, BACKPACKER's gear editor swears by Mountain Hardwear's Compressor jacket. This lightweight puffy coat packs as small as a grapefruit and is filled with Primaloft, a synthetic insulation that holds its loft and keeps insulating even if you dunk it in a cold pool. It comes with or without a hood, and features a simple, flattering cut.
5. Wetsuit: A full wetsuit would almost always be overkill for Zion Narrows, which rarely has water deeper than your knees, but it's a key piece of equipment for serious slot canyon aficionados who plunge deep into the Southwest's darkest, wettest canyons in the off-season. That's when pools are at their deepest, and in places like Buckskin Gulch you might be swimming for a hundred feet or more.