I can tell you in all honesty that I have been searching for the last wayshrine for nearly 3 hours now and I can find it. In the Glacial Crevice I just keep going around in circles as with the Falmer camp that winds around the cliffs' edge. I am at my wits end trying to find this place. I have to way points on my compass and no matter which way you go both are on either side of say, North, or South, East or West. The first time I played though Dawnguard, I found the last wayshrine totally accident: and, I mean totally by accident. I have even watched a couple of walkthough videos too. If I go back to a save before I stated the quest I will lose a level up on my character. Does anyone know exactly where I need to go or a cheat code to get me there? Thank you.

Dawnguard forums, maybe?

Huh!

By last do you mean the one right near the entrance to the Chantry? You need to go right through the Falmer gorge section until you come out the other side.

Again, I found it by accident. Thanks.

the last wayshrine is bugged, if you're on PC you can use console commands to port you to the last quest objective if you have alot of difficulty finding it. For whatever reason the last wayshrine waypoint points towards a wayshrine you've already found.