I took a paddle board upstream for about a mile. The water meandered through open pasture land with views of neighboring mountains. There was very little shade and not a whole lot to see, but it was quite peaceful and I did not see anyone else. I finally had to turn around about a mile in when I hit a logjam, literally. I could have portaged around through grass and mud, but I figured I would save that for another day. I guess the river goes a little further before becoming unnavigable by board or boat.
On a future date, Emily and I plan to explore the Kapaa Bike Path.