At about 2am I got up to go for a pee, only to be confronted with a portly young woman who wore white wellington boots and brandished a mop. As I was standing at the urinal she said a cheerful hello - revealing in the process that most of her front teeth were missing - and went on to tell me how the sinks were often dirty because swimmers and campers would tramp in from the beach and wash their feet in them. Quite why she was cleaning the toilet block in the middle of the night was anyone's guess, but she was very jolly, and I complimented her on a job well done before going back to my tent.
At a michi-no-éki later that morning, I encountered two cyclists who had met on the road and decided to ride together to Wakkanai. One was Mr Abundant Fortune, a university student in Yokohama, and the other Mr Circle Field, at seventy-two years old approximately fifty years his senior. Smiling, tanned and with the aura of a Mr Motivator-style daytime TV fitness instructor, Mr Circle Field said that he used to be an engineer at power plants and had worked as far afield as Saudi Arabia.
'You never know,' he said. 'I might be laid up in bed terminally ill this time next year, so I'm getting out and about while I still can. Take my advice, though, and have kids sooner rather than later - you don't want to have to look after them when you're old.'
'I can't imagine you'd have too much trouble,' I said, and thought that this is exactly how I want to be when I'm in my seventies: still fit and still cycling (Mr Circle Field's only concession to age was the bandana he wore as a mask - 'To keep out the exhaust fumes,' he said).
'I ate for free last night,' he said cheerfully. 'The staff at a convenience store were throwing out some bento that had passed their sell-by-date and said I was welcome to one if I wanted it.'
The most notable incidence of this happened in the Toyohama Tunnel west of Sapporo one morning in 1996, when an estimated 27,000 tons of rock collapsed onto the unfortunate occupants of a car and a bus that happened to be passing through it at the time. Twenty people lost their lives, and when it was eventually dug out, the bus had been flattened to a third of its original height.
As a cyclist, though - and much more so than being crushed pancake-flat beneath an entire mountainside - the tunnels of Hokkaido are dangerous because, with a few notable exceptions, they are narrow, poorly lit and often devoid of a pavement. Even if there does happen to be one, it will more often that not barely be wide enough to cycle along, so high that should you veer off the edge and onto the road your front wheel will buckle from the impact, and lined with SOS telephones that protrude from the tunnel wall just that little bit too far to enable you to pass them comfortably. Not only that, but the gutters you ride through instead will be awash with a filthy cocktail of ground water and engine oil.
Of course - and having said all that - sod's law dictates that if I am ever unfortunate enough to kick the bucket on my bicycle, it will not be beneath the wheels of a twenty-ton truck or in the murky depths of a tunnel, but by a Nissan Micra, on a sunny day, a straight road, and while wearing the most brightly coloured and highly visible clothing in my wardrobe.