About 20-30L capacity, should be waterproof membrane and not just a coating on the material.

Does not need to be submersible just needs to stay dry in a tropical thunderstorm.

Budget : less than $150 please...

Any recommendations??

True North makes some nice waterproof packs:

http://www.truenorthgear.com/product_listing.php?path=0_1

I do not know of any waterproof bags.
However, my EAGLE pack was out in a medium rainstrom for a day, no leaks. Factory waterproofing only; it is brand new (just about) and I had not modified anything yet.

If you can stand a couple extra ounces of weight (and you're not 100% in the rain, and you have an existing favorite pack), a good system is to use a Seattle Sports Drybag (L/XL = 2500/3500 ci) inside your pack. XL weighs 26oz. and costs ~$25. And you can use it for canoe/raft/drift trips.

that's actually a good idea.

Checked out True North packs... nice!

will do a search for the drybag..

thanks guys..

I use Sea to Summit EVent Compression Dry Sacks inside my pack for my down sleeping bag etc. I have never had great luck trusting anyone's waterproof anything, jackets especially. I will also use industrial large ziplocks to keep gear in, usually clothes. A hefty bag liner for the pack is also helpful at times.

Bottom line is that I use a multi part solution because of Murphy's Law.

Trouble with water proof packs is they not only keep water out, they will also keep any water in.
A better idea would be to use a survival sack inside your pack to keep your stuff dry ! This way your whole pack could also be placed into the survival bag ,tied and used as a floatation aid if ever required to do any river crossings etc !

I'd agree with the consensus on this one, pack your kit in waterproof sacks in the backpack.. Good enough for the Royal Marines, good enough for anyone! I use small heavy gauge plastic rubble sacks to pack kit in, inside a 6X4' survival bag inside the pack. I've never had a leak yet in 20 years... I think I remember a company called Macpac making what they *claimed* were waterproof packs but I've never tried one.

Sometimes if I want to waterproof something I’ll use multiple layers of ziplock bags, one inside the other like nesting dolls.

I actually use what everyone here mentions, ziploc bags and then a waterproof sack inside my pack. I just thought that a dedicated waterproof pack might be lighter thats all.

But looking at some of the dedicated waterprrof packs, they look like they don't have a good and comfortable carry system, are quite heavy and some are downright butt ugly to boot...:)

The True North pack are peculiar, but they are very comfortable.