Enterprising young Swedes would set off in their boats for the port town of Viborg, load up with vodka and return to sell their spoils in Sweden at a vast profit. This is what is known as unbearable temptation.

A shivering sailor in the open Baltic would open a bottle and take a sip, just to warm his bones you understand. He would only do it now and again. And again and again. And again. Strangely he kept finding that there were empty bottles lying in the bottom of the boat, so he threw them overboard to avoid being thought untidy.

You have to realise that it wasn't just one tipsy sailor, but all of them, and it wasn't just one voyage, it went on for centuries. After a while the discarded bottles became a navigation hazard, but at least the piles of bottles sticking out of the water gave the sailors something to aim at, so they soon built up into islands.

You can imagine that as the channels got narrower, and as the sailors weren't at their best, navigation became a problem. Sometimes a crew got so lost that they took the obvious solution. They landed on a convenient island and shared a bottle. And this is how the land of Finland became populated."