Designed by ex-Israeli Military dudes, the 3N1-20 Sling Bag is specifically designed for the hardcore photag.  It can be carried in three positions, eash catering to different scenarios.

1. Backpack style for long hikes
2. Quick draw, which engages one strap and allows the bag to be rotated to the front of the body allowing quick access to your camera and backup lenses
3. X position, which provides backpack comfort and similar accessibility and speediness as quick draw

More importantly there’s an ass load of pockets and areas to strap in your equipment and you can choose from 3 different sizes depending on how hard core you are.

Product page here

[Core77]