Ok, I know they are new boots but I have never had this problem before. The fit is fine and wore them with hiking socks but on a 8km walk which I do every morning I received a massive heel blister on each foot which has stopped me walking. This is not what I expected from Keen. When I feel inside the boot there is a ridge around the heel areas that no doubt caused these blisters. I'm not sure if trying to 'break in' these boots gently will help as its difficult to just go for short walks and then have to change footware. I am also not convinced about the waterproof claims as when walking through grass I felt moisture on the top of my feet and I can only surmise that there is no membrane inside the small 'joining flap' between the boot and the tongue... I know as a leather boot they are stiffer than suede/mesh ones but I am not sure I will be able to live with these.