Craig Hall has thru hiked the AT, the PCT twice, the CDT, Long Trail, John Muir twice, Foot Hill Trail and worked in Yellowstone National Park. He currently travels the country as an ENO rep and is an awesome photographer. Listed below are Craig's recommendations of what to take on a day hike.
1 Footwear is the most important thing. A good trail running sneaker like Montrail, Brooks, New Balance, Vasques, Solomon,...
2 Shoe Inserts - I prefer Super Feet.
3 Socks - merino wool
4 Trecking Poles
Under layer - short sleeve of natural fiber
Base layer w/ hood
Outer layer - fleece with zipper
Outer shell - raincoat (Gortex)
Same idea for your bottom half (swim trunks, tights, fleece pant, rain pants)
6 gloves, fleece hat, ... depends on the weather
7 polarized shades
8 30-35 liter pack (Granite Gear, Lowe - if you are taking a big camera)
10 bug spray (doTERRA's Terrashield and Lemongrass in a spray glass 4oz bottle)
11 trowel and toilet paper (always burry your waste 6" below)
12 head lamp
14 map and compass
16 water and a filter if you will be out all day (Sawyer)
18 eno hammock and straps, of course. :)
19 I take a camera and tripod everywhere I go. There is always an opportunity for great pictures in nature.
Check out my facebook page for some of my photographs.