Atlantic cod are deep water fish. Except in the spring.
This is when the smaller fish get shallow in the kelp beds hot in pursuit of small orange crabs. Cod eat these crabs until their bellies look like a lumpy bumpy sack of oysters.
I have tied Mark's Cod Crab on 2/0 hooks with double dumbell eyes, velcro, latex sparkle paint, and rubber legs. Cast on either a shooting head (best) or sinking line, it heads to the bottom at a slant, just like a real crab.
Who can resist those wiggling legs? Not a cod!
You can self guide, but if you can find a guide who fly fishes (not many guides do this), hire him or her because I have spent too much time fishing what turned out to be cod-less spots.
The entire Norwegian coast is the most accessible area, but wherever you go, don't leave home without crab flies. If you fish Greenland then the West Coast is best.
Atlantic Cod are common across the North Atlantic, but you need to be in a spring spawning area to fish this fly.