A contender for probably Feedback’s favourite-ever unusual unit arrives in an email from Mark Dowson, and it has the more unusual cachet of likely great antiquity. Apparently, reindeer are unable to walk and pee at the same time: they have to pause at set intervals of distance.
In Finnish, this interval is known as poronkusema or “reindeer’s piss” and was an old-fashioned description of rural distances. By Mark’s calculation, it is about 320 blue-whale-lengths.

This is a WikiFact, but it seems almost too nice to be true. So Feedback asked a friend — the Finnish journalist Heikki Jokinen. He confirms that it is used in Lapland and was delighted to be diverted from other work to discover its actual value, which is about 7.5 kilometres for a reindeer drawing a light sledge — and that it is important: reindeer eating lichen produce urine as strong as battery acid, he says, and they get sick if deprived of their comfort breaks.
From “Feedback”; New Scientist; 22 March 2014