Some backpacks are waterproof, but like a tent, the seams need to be sealed.
Waterproof Pack Cover needs to be large enough to protect items strapped to the exterior of the pack.
A couple of large garbage bags may be suitable for summer hiking in the Sierras, but if multiple rainy days are anticipated a dedicated pack cover is better.
Down bags are not good because they are ineffective when wet.
The sleeping bag should have a comfort rating from 20° to 30° and should weigh no more than 3.5 pounds, but preferably less.
For extended treks the internal frame pack should have a volume over 3,000 cubic inches (50 liters), but less than 4,200 cubic inches (70 liters).
The larger the pack, the greater the tendency to fill it with non-essentials.
There is lots of discussion about the proper amount of weight that a boy can carry safely.
It varies wildly, depending on the attitude and strength of the boy.
Save weight by building your own First Aid kit with a Ziplock bag and supplies.
Water Bottles: Two wide mouth plastic water bottles (32 ounce size) that fit inside the larger side pocket of most packs are great but their are lighter options.
Sleeping Bags are available in many sizes, fabric, fill, color, and price.