Ditto Hikermor.

There are some things I like having immediately handy on a lanyard -- such as whistle and e-PICO light. I carry those every time I walk out my door, on a lanyard with my house key. Those items could also be attached to the front of my backpack's shoulder straps.

With my daypack, I attach to the hip belt a small LL Bean fishing gear bag (since discontinued) that has ample room in the smaller front pocket for Doug's PSK, plus more. I also keep in there a Kleenex packet, antiseptic wipes, lip balm, lighter, big compass, Doug's MK1 folder, and more. My hip belt also has two built-in zipper pockets. It's nice to not have to dig through the main pack for the small stuff.

That LL Bean fishing bag is something I wish I'd bought extra of, it's so handy. It measures 8"(L)x7"(H)x2"(D) and also makes a comfortable place to prop my left arm while hiking. I keep an eye on fishing gear to see what else could be useful for hiking. Could be wise to break the PSK up. Would a fish hook be useful on the volcano?

BTW, the pack in this photo is the previous version of the LL Bean Bigelow.

Click on the link below the photo for a closer view.