I swear by Sealine packs.  I've had my personal pack, about a mid-sized pack, over 15 years.  It gets used multiple times every year for a week or two at a time, and is still going strong and is still reliably waterproof.  They make a couple smaller models.

Was surfing for another tent and came across this water proof bag (You need to Login or Register to view media files and links)  holds 27 liters

zski wrote on Sep 15^th, 2012 at 12:18pm:

If you go with this one, go to retailmenot.com and pick up a 20% off coupon.  That puts the price just below $60.00.  (If you buy other items, you could possibly use a deeper discount coupon, since the current price is right at a break point.) 

I do have a smaller version of this bag which I used as a kitchen pack for this season (e.g., pots, pans, utensils, stove, fuel, reflector oven and other odds and ends).  It has a zip top closure which you can then roll down and buckle if you don't overfill.  I didn't have a chance to dunk it, but did fine with a couple of hard rains and wind.

dd

Sierra Trading Post has a Columbia Dry Bag Backpack (You need to Login or Register to view media files and links)
(You need to Login or Register to view media files and links) $74.95

Maybe this will fit the bill db Outdoor Research Dry Peak Bagger Back Sack $42.99 - Campmor

Today my new Gossamer gear Gorilla pack arrived.  It is mostly a one big pocket type of pack.  I plan on using it as a second pack more than a day pack.  For me the one big pocket is not a problem.  You may want separate pockets to keep gear sorted.   It is light and carries a 30+ LB load very well.  I will be able to ware it while carrying the canoe. Check them out (You need to Login or Register to view media files and links)

I'm looking for a daypack that will hold 2 sets of raingear, lunch, skeeter spray, sunscreen, water bottles, etc. Probably about 3000 cu ". Should have pockets to allow easy access. Doesn't have to be waterproof, but that would be nice. Any suggestions?

I bet you could use Azalea's bag as a pfd.  Those look like the same zippers found on a drysuit.

A close-up of the zipper.

My waterproof bag. It has two pillows inside, the front of the pack is clear vinyl so you see the white pillowcases through that.  A ruler is in front for size perspective.  Easy access via a zippered opening, but I do not know how well it would keep out water if the pack was capsized into a lake.  In the rain, it has kept stuff dry.