My most memorable one - I was Steelhead fishing in the Sydenham River, Owen Sound, Ontario. Spring a few years ago. Method - 13 foot float rod with center-pin reel; leader - 3 lb test due to clear water, # 16 hook with single salmon egg bait.
I was fishing in the middle of a long deep pool when the float went down, I set the hook and I knew it was a good one. The fish ran upstream - no problems there! Then it turned and went downstream, then back upstream,and back down again. Note: that river is not very wide. We battled it out in the pool for several minutes. Never saw the fish. Then it decided it had enough of playing games with me and headed downstream - heading for the lake (Owen Sound Bay off Georgian Bay). Not wanting to let too much line out I followed along the bank as best I could, calling out "fish on" so other anglers would give room. I followed for several hundred feet until I got to a fallen tree I couldn't get past with the rod. That fish seemed to know it and put 'er in high gear. I held on. Must have had 200 plus yards of line out and that fish never slowed down. Finally too much drag due to the extent of the line out (I guess) and the leader popped
.
I still wish I'd have a least seen it! Best one I ever landed was approximately 12 lbs, and I'm sure the one lost that day would have been considerable better.