I already mentioned this, but due to its recent success and ease I thought I would say again.
At Horseshoe Inlet there are 3 creeks to cross, two of which you can reportedly wade by going out in the bay. Not for us with those large waves due to the wind, so we swam all 3 creeks.
A good view of the creeks
here.
Turn pack upside down
Carefully place large orange garbage bag with yellow ties (77 grams each) over the pack, turn pack right way up and pull orange bag up, twist it up a bit and wrap a rubber band around the top a number of times to make a tight seal. I carry a number of size #64 rubber bands, they are great for all sorts of things, including this.
Be careful not to pierce bag on sticks or rocks.
Person 1 swims across without pack.
Person 2 picks up pack and places in creek, bit of a push in the right direction. Allow th +100kph winds to carry the pack across the creek. Person 1 retrieves packs from water.
Take off garbage bag, store safely so it doesn't snag / rip, ready for next crossing, continue and do it all again another two times.
Of course if there is no wind, swimming across with a cord / string / rope would allow the packs to be pulled across. A large quantity of builders line (white nylon string) is a handy thing to carry, lightweight, good for all sorts of things inc. clothes line, emergency bootlace, extra guy line if needed, and pulling packs across creeks.
One other thing I noticed. When I swam the Irenabyss I noticed it felt positively warmer when exiting the water. I noticed this again when I got out of the first of 3 creek crossings a couple of weeks ago. But exiting creeks 2 and 3, it did not feel warmer when exiting the water, and hypothermia was a real danger.