I recently purchased the Mountainsmith Cairn Lumbar Pack (1100 cu in) and used it during a series of day hikes in western NC. This pack was perfect for day hikes. I comforitably carried everything I needed without much noticing the weight. I used two 32oz Nalgene bottles for water. The only issue I encountered was the bottles were too large to be secured by the bungies in the provided pouhes. I found that when climbing over rocks the bottles could be pushed out of the pouhes. I solved this with some thin nylon cord (4ft each side) which I tied an end o line bolin to the pack and then a slipnot aroung the neck of the bottle. No more issues. I am extremely happy with this product.