Thank you Caer, I now feel proud of my idea.
So secret underwater/underlava layer it is then. I reckon we should build stuff first, then flood the place otherwise it'll become a lil' difficult. Why did Notch remove the usefulness of sponges? :-@
I'd like to know why he changed water - it used to be that you could dig into the sea and water would flow untill it all reached sea level - not anymore
I'd also like to to know why I didn't have this information untill after I had dug a big/long aqueduct to flood 'the hole'