1. Daypack. The capacity you need depends on weather conditions and what you'd need
to survive a night out. Count on extra space for photography equipment or other gear for hobbies like drawing or fishing. We like EMS's Waterslide ($79), a 1,650-cubic-inch daypack with side-compression straps for lashing extra gear and a removable hydration pack for lightly loaded, warm-weather hiking. Contact: Eastern Mountain Sports, (888) 463-6367; www.ems.com.
2. Food and water. Sounds obvious, but many dayhikers underestimate how much fuel they'll need for a 12- to 16-hour day. Pack two lunches and a few snacks or energy bars. Check water availability; if you can't refill along the way, carry a few quarts, more in hot weather.
3. Headlamp. Test it before heading out, and pack extra batteries if you expect to be hiking in the dark.
4. Basic first-aid kit. Think about the stuff you'd need to patch injuries long enough to hike out--a few bandages, some antiseptic wipes, and butterfly bandages for wounds, a triangular bandage (also works as a sling, bandanna, and athletic wrap), and tape. Adjust for longer outings and group size.
5. Map and compass. Don't take navigation for granted just because it's only a dayhike. Ten miles from the car is still 10 miles into the backcountry.
6. Water treatment. A bottle of iodine tablets or other chemical treatment adds mere ounces to your pack, but pays off on long days when you're constantly refilling your tanks.
7. Rain shell. A lightweight waterproof/breathable shell is ideal. A poncho also works and may take up less room in your pack. Toss in an extra midlayer if the weather is chilly.
8. Emergency shelter. Depend-ing on your preference for pack weight and comfort, all of the following work: bivy sack, emergency blanket, tarp, a waterproof rain suit. Consider carrying a lightweight sleeping bag if nighttime temperatures would kill you.
9. Warm hat. It won't take much space in your pack, but provides the warmth of an extra sweater if the mercury dips or if you have to sleep out.
10. Fire. Lighter or matches in a waterproof container.
Recommended extras: Sunscreen, insect repellent, emergency whistle, sunglasses