Sony HDR-AS100

I have a AS15 and 2 of the AS-10s.   bsteves comments pretty much state what most reviews / comparisons to the GoPro line have assessed.   I was a little dismayed how a year after I bought them from Walmart, they were closing them out.  My main use for them is for track days so can't provide much to say regarding Kayak use.  One negative is there are far fewer accessories out there for mounting them compared to what you can find for the GoPro's.   
  This YouTube reviewer has some interesting and informative videos of the Sony's and GoPro's.  He has also reviews some inexpensive cameras which look to be worth considering.

https://www.youtube.com/channel/UC5I2hjZYiW9gZPVkvzM8_Cw