3 ways to navigate in CryENGINE Editor

1. Hold down middle-mouse (mouse-wheel button) and move the mouse around to pan. Hold down the right-mouse button and move the mouse to look around.
2. Use the W,A,S,D keys to move forward, left, backward, and right correspondingly.
3. Use the middle+right mouse buttons together to fly around the scene by moving the mouse around. Scrolling the mouse wheel also lets you move forward and backward.

Bonus: Holding SHIFT speeds up camera movement.