Some of the barriers can be removed. You'll have to explore the teleporters (in your human form) that are scattered around the fjords to find the switchches to remove them. Look for a well-guarded fortress.
There are also some barriers that can't be removed, although you'll be able to fly past them to proceed around the fjords. But to reach the areas inside them you'll have to switch to human form. This will occasionally require you to swim or walk instead of flying...
