Some people watch racing cars, others birds. Some stand on platforms awaiting a certain train, and there are even those who wait on motorway bridges for Eddie Stobart lorries. It matters not what the passion is, but for those people who endure the elements in pursuit of it, I know the feeling - my passion is fish.
In this case, Atlantic salmon. Not the pink-dyed, lice-covered lard-arses found in supermarkets. Im talking about wild ones - fish that grow up in the shoal of hard knocks. Fish that dodge marauding perch and hungry herons as fry, and then fight natures ferocity to come back to their river of birth.
This magnificent creature travels to Iceland and, when the time is right, evades fishing fleets, seals, otters and dolphins to find home. It sniffs out the water, goes on hunger-strike; changes its body and leaps waterfalls. And it was this last point for which I was waiting.
Every few minutes a flash of colour dived against the flow as a wild Atlantic salmon strove to find home.
Yet, as a diver, I wanted to swim with this wild fish in its environment - which is what I set about doing.
Inland waterways are controlled. Just jumping into a river was not an option - unless I wanted to try to explain what I was doing to a river bailiff with the powers to arrest me.
Anyone wanting to dive a river must seek permission from the land-owner and controlling authorities, so I sought the fisheries boards blessing to get into the River Braan.
That granted, I started to research places for diving, and drew a blank. No one had dived here, so I spent a few days visiting promising locations.
Most were too inaccessible for a man in heavy kit, or the water was running too fast. I needed a confined space, so that the fish would have no choice but to be close to me.
I settled on a particular pool slightly down from a large waterfall that the salmon couldnt leap. Its the end of the line, but the fish dont know it.
Their instincts tell them to push further, so they bunch up, and this provided me with the chance I needed.
Mid-September is a good time. The water was low thanks to a lack of rain, but peat stained it brownish.
I clambered across the boulders at the edge of the pool and drew a crowd that had come to watch fish jump out, but instead saw a crazy fool climbing in.
The visibility was like weak black tea, and if it wasnt for the sun streaming down the valley, I probably wouldnt have seen much at all.
The pool was 3m deep, and too wide for me to get close to the skittish fish, so I pushed into the current and headed for the narrow gully between this large pool and the splash pool directly under the waterfall.
It was darker than the inside of a dog in the gully, and the current was pushing hard. I wrapped my legs around a boulder in the bottom and waited. Ahead of me I discerned movement, but it was lost in the gloom.
And then a silver flash passed me - my first view of a salmon under water in the wild.
As I stayed still, the fish grew accustomed to me and started to drop back. I could see tails flicking just ahead.
Then one female came level with me. About 50cm long, she wore the scars of her journey, tooth-marks from a dolphin from which she had escaped. Two more passed overhead, and soon I was ignored - I had become just part of the riverbed.
When I breathed out the fish moved away, however. Then they came back. They seldom came close enough for photography, but the few close passes I got were enough.
I was elated. I unfastened my grip of the rock and was spat out into the pool. I surfaced close to where I had entered.
A few of the onlookers came down to see what Id seen, and said they had watched a few fish try to leap the falls. They were fascinated by the jumping, as this is one of the few times a non-diver gets to see a living fish in action.
But I had seen something few people will ever see - wild salmon, swimming in their natural environment.