Styles vary, as do personal preferences. But whether you are a backpacker, a mountain biker, a hiker, a trail runner, or simply someone who has found themselves out on a trail somewhere, there are a few supply-chain constants that you should always keep in mind.

"I'd like to say that I've always subscribed to the thought that, ‘Well, if it isn't in there I probably don't need it,'" said Tim Twietmeyer, a five-time champion of the Western States 100-mile Endurance Run, which takes trail runners from Squaw Valley, Calif., to Auburn, Calif., each June. "But there are some important essentials that you should always have with you."

Such as:
1. Water. You can probably forget just about any other item except this one. As Norm Klein, a longtime race director from Sacramento, Calif., used to tell the runners in his trail races; "No one ever died from blisters or scratching their knee. They have died from not enough water, though." Use durable plastic bottles or backpack models such as the Camelbak, some of which can store more than 100 ounces of water.

2. Iodine tablets or water purification filter. Water in the wild, depending on where you are, can be perfectly fine – particularly if there are no livestock or wildlife that can pollute a water source. To hedge your bets, though, carry one or both of these items to avoid intestinal diseases such as Giardia.

3. Topo map, or GPS unit. Topographic maps will clue you into area around you. Find trail guides in advance of your adventure in order to familiarize yourself with the area.

4. Compass. Yes, we have GPS units, and they are a great help and have been a great innovation for hikers over the past 10 years. GPS can get spotty, though, particularly in wilderness areas. It's hard to beat a trusty old compass.

5. First-aid kit. The typical first-aid kit should have enough bandages and gauze to cover most minor emergencies, plus pain reliever, a variety of clippers and needles for blisters, moleskin for blisters. A great investment is to purchase a first-aid book that explains what can go wrong in the wild, and how you can treat certain injuries. Knowledge beforehand is probably the best preventive measure you can take.

6. Knife. The Swiss Army knife still sets the standard. It's versatile, and it's effective. The variety of blades and tools can be a life-saver.

7. Light. Most of us expect to be done before dark, but trail distances are sometimes notorious for their inaccuracy. A 12-mile hike might take you an extra hour or two due to the terrain. If it gets dark, a lightweight light of some type could be all you need to find your way back to the car.

8. Matches. Just in case. You never know if you are going to spend an unexpected night in the wild.

9. Food. Make sure you have plenty of variety. For some people, energy bars or gels are the way to go. Others prefer solid food. Or a combination of both. Either way, make sure you have a bit more food than you need. Your companions may need the extra pick-me-up near the end.

10. Layers of clothing. Always dress in layers, and bring layers with you. Even if the day is supposed to be 95 degrees and no clouds, if you are in the high country, the odds are good the wind will come up in the afternoon. A windbreaker could come in handy.

10A. Sunblock and sunglasses. Take it from me: Now that I'm making semi-regular visits to my dermatologist because of pre-cancerous lesions on my head and ears, it's imperative to wear sunblock. Slather it on early and often. Sunglasses serve the same purpose for your eyes. You'll grow less fatigued if your eyes are under less strain. Plus, you minimize the possibility of cataracts later in life. Both are worth the investment and the extra effort to use them.

* Who are the Mountain Mutts?
This week's Mutt is John Trent. John's been partaking in the trails of the Sierra since he was 11 years old, when he got lost on the road leading from southwest Reno to Hunter Lake near the Mountain Rose Wilderness (yes, eventually he did find his way home, but not after getting really sunburned and running out of water). Since then, he's run the Western States 100-mile Endurance Run from Squaw Valley, Calif., to Auburn, Calif., eight times -- seven of them in under 24 hours. He's a former Outdoor/Recreation editor for the Reno Gazette-Journal who still regularly writes and reports on outdoor recreation. He lives in Reno with his wife and two daughters.