@Huntster I had a similar experience with a moose at a lake in central BC. A long time friend and hunting buddy spotted a nice bull swimming across a small lake towards him. He waited for it to come out of the lake; it walked about 10 yards from the shore, shook like a dog to get the water out of its coat, then turned sideways, presenting the perfect shot for Robert to take. He put one right through the heart/lung area and watched the bull lurch back into the lake and start swimming back to the other shore. It died trying to climb out the far side of the lake. I showed up about then, having heard the shot. We spent half a day struggling through the willow swamp at the end of the lake to get to the moose, by which time it was snowing. Like you, I stripped down, waded out on the mucky bottom to tie a rope onto his rack, and we pulled the whole body far enough out of the water to get it gutted, skinned and quartered. By then it was dark so we left it there for retrieval in the morning.
It took two days to haul the quarters out to the logging road. On the final morning, arriving at the carcass, we were greeted by a hissing pine martin, who was claiming the last load for himself. After repeated attempts to scare him off failed I had to shoot the little critter to get to the meat. My wife still has the lovely pelt on her dresser, 35 years later.
We really needed a boat or an Argo for that one. I bought a used Argo the next year, and only ever had to use it once to retrieve an animal in the 10 years or so that I had it.