On our very first cruise we did the 'float trip' on the large 'rafts' Sorry I don't remember the name of the excursion but it was it superb! Beautiful scenery and lots of eagles around
It was a very smooth ride not 'white water' rafting. I have a lower back problem and I was fine, there was also a pregnant lady in our raft
We took a ferry from Skagway to Haines and then a bus to the river.
I think we booked it through the cruiseline.