Further and further I run, covering vast distances, until... I reach the end of the cave, and what looks like daylight! I don't believe it! The sky... the horizon curves upwards... I can see oceans, continents... and an inner sun.. Planet earth is... hollow!

And in the distance I see a ship... I recognise it! That's the arctic research ship where I used to work! Somehow the must have sailed to the edge of the world and down inside!

Should I join my friends? Or should I go back and tell my uncle? Or do something else?