For years I'm carrying the knife on forearm, on the exterior. I'm a lefty, so I have on the exterior of my right forearm, handle towards the hand, point towards the elbow. If you are concerned about access with both hands, add a 2nd knife on your left arm.
So far it worked well:
you can reach it even if you bear hug a fish, and a hand is through the gills. You can see when you put it back. Not in the way when loading a gun. Less chances to tangle, and easy to untangle.
I used to have the knife on my calf, it was prone to tangles (float line, fishing line etc) and I didn't like the small holes in my suit.