We have an old, black Sealine dry bag (a big one) that we have used for many, many years now and will finally have to replace this year.  I would have to look up a lot of albums and go back to see how many years, but I am thinking probably 15-16 at least.  It has not been babied.  The bottom seams are finally starting to fray and we said this year that it is time to replace, but we will probably replace it with another dry bag because it has been comfortable to carry and has done exceptionally well at keeping sleeping bags and other such items dry.

It doesn't have a hip strap, and I know that a new one will.  That will be an improvement, but even without one, it was my favorite pack to carry.  It was packed with sleeping bags, clothing pack, paperback books, dry shoes, our medicine bags (which became substantial as years went by--severe arthritis pain issues for one of us, and diabetes, kidney disease, kidney transplant, etc. . .for the other), and a few miscellaneous items like the headlamps.

It is waterproof, floats, and I found having it right behind my seat when I am in the canoe makes for a nice "lean-back" for resting occasionally.  Far better than a canoeing seatback.   :)  I love my big rubber bag! ;D