The Geo Waist Pack by Estwing is a high quality pack for carrying the things that you need in the field.
Estwing Geo Waist Pack
This is a great waist pack to carry your testing supplies, instruments, camera, or small specimens collected in the field. It is light-weight (about 15 ounces) and has a durable adjustable belt with strong plastic snap closure. Just squeeze to close, squeeze to open.
The pack has three compartments (see dimensions below). The two main compartments close with a zipper that is covered by a flap to shed dirt and moisture. The pouch on the side has a thick velcro closure and can easily carry an iPhone or other small device. Pens, pencils, a pocket knife and a hand lens can be carried in a side pocket. A tiny carabiner (provided) is on a loop beside the pocket that can be attached to a cord or loop on your knife or hand lens.
Outside Dimensions: Height 5.5 inches, Width 8 inches, Total Depth of 4.5 inches.
Large Compartment Dimensions: 8 wide x 3 deep x 5.5 high
Small Compartment Dimensions: 8 wide x 1.5 deep x 4 high
Side compartment is large enough to hold an iPhone or similar-size device or a folding phone and secures with a velcro closuer.