Very comfortable.  Putting on and taking off my boat shoes used to be an ordeal.  Then my insoles started to come loose.  These socks make it easy to put slip on the shoes and take them off.  The brown color matches the shoes well, but you can't see them once the shoes are on.  They don't slip off your foot due to the thin piece of rubber at the heel.  I've even walked around with just the socks without issue.  One of my favorite buys of all time.