1. Food and Water:  Even if you think this hike will take only an hour or so and they just ate, kids can be as unpredictable as the weather.  You do not want to be stuck hunkered down waiting out a rainstorm or re-tracing the path toward the trail you missed and have a hungry or "so firsty" little guy or girl on your hands who is also exhausted from hiking, and consequently a bit more emotional than usual.

2. Plastic baggies:  Perfect for carrying new collections of pebbles from the ground or for carrying the wet clothes of a potty training oops (going potty on the toilet and going potty in a bush are two different things and sometimes that can make my own little one a bit nervous).

3. First Aid Kit:  This one is pretty self explanatory.  From blisters to splinters, all sorts of small boo-boos need regular attention on a hike with your kids.  Hurt feet from blisters or other maladies can quickly turn a fun day into a painful experience, which brings me to:

4. A Good Pair of Shoes: Because our grown-up feet are on our own body, we know the importance of good footwear, but it can be easy to forget that your little one's tootsies need pampering too. 

5. Baby Wipes:  Even with older kids there is always a job to be done for these handy little wipes.  Cleaning shoes or hands covered in mud, or simply wiping away sweat after a long day are just a couple of the uses of these little babies.

Stay tuned for other top 5 lists.  Did I forget anything on this one?