The "Rolls Royce" of outdoor camera carrying were the Camera Care Systems padded pouches, which could be worn on a hip belt or shoulder harness. The company is sadly defunct, but 2nd hand stuff is still available on Ebay. These days I just carry an X100 slung over my shoulder on a thin neoprene strap.
When I carried an SLR & spare lenses they were fine in a bar bag over rough terrain (Iceland & India), but not the best for instant access.