This is the perfect bag for the traveling photographer. I used this for our sailing trip to Thailand as my only bag and it packed in so much gear! Camera gear: body multiple lenses, batteries. Climbing gear: Shoes, harness. And of course clothes and swimsuits and everything in between.
It's a little excessive for the day hiker but for a multi-day trip or if you need to bring a lot of camera gear, it's perfect.
There's a standard edition and a deluxe edition. The deluxe includes some attachments and extenders. Shop on Think Tank Photo
(and choose a free gift with purchase when you use my link) Shop on Amazon