Dave has posted a debrief of his Missouri swim and it puts the reality of his undertaking into grim perspective. In the article, he talks about the physical toll that this journey took on his body, getting to the point in the final days where he couldn't keep food down, despite the fact that he was burning 6000 calories per day. Swimming from sunrise to sunset, day in and day out, sapped his strength and spirit, pushing him to the very edge of his limits. It is a very personal account of a person who is completely at the end of their rope, but refuses to give up on his dream.
Reading Dave's account of those final few miles to the finish line are not easy. He clearly had pushed himself further than even he thought possible and yet as he neared the end at last, it still wasn't nearly enough. Of course, we know that he did manage to complete the swim, but Dave describes the days that followed as "darker than any other post-expedition experience I care to remember." No doubt, that was the result of complete physical and mental exhaustion he felt at its completion.
Now that some time has passed, Dave's attention has turned to the next phase of Expedition 1000 – a 3000-mile (4828 km) journey around Europe on ElliptiGO bicycles. While this is a completely different kind of mode of travel, I'm sure he'll take with him some lessons from the Missouri River.
If you want to know just what an ordeal that swim was for him, then his blog post is a must read. It will definitely give you even more respect for what Dave, and other adventurers like him, have accomplished.