Avlantis

Once upon a time there was another island that was part of Avalonia, but that island has been lost to the waves of history and had sunk all the way to the bottom of the ocean. There is a very famous myth about an island that had became a whole city, every inch of its surface was covered with structures of different sizes and heights and many thousands of people were living on it. They had built so much things they have erradicated every bit of greenery that was originaly on there. After a while the island became so heavy with their inventions and new buildings that it started to crack under the weight of it all. The cracking intensified and soon enough the island was unable to resist the deep calling of the ocean and disappeared forever beneath the waves.
People use this myth as a cautinary tale of what will become to people if they chase after knowledge way too much and try to fix and build and invent mechanisms to improve the world around them. They will fill it with so much metal, the nature would die and the water would come for us all. This is the reason why it is so often told to young kids to scare them away from school and any forms of education. 
On the other hand nothing quite works as a deterrent of school like the institution itself, so many youngsters do not need to be told twice that education leads to terrible horrible things. But what fascinates them the most on this story is all the weird and wonderful things that could have sunk deep down into the ocean with Avlantis. And if the island truly existed in the past, surely people have been trading and visiting the other Avalonian islands as well right? There must be some traces and treasures left behind all over the kingdom from this fascinating floating city of old.
This myth is a reason why so many adventurers and treasure hunters are born. And skip school.