They are like those monsters they found in the lowest depths of our own seas.
They can only live under tremendous pressure.

That's why we didn't find any of them up above.

This chap'll burst like a bubble presently.
Meanwhile, there's no use in stopping here.

Suppose you go below and brew some coffee and bring it up on deck while I go and see how things are looking aft.

It doesn't do you any good, you know, to be looking at monsters of this sort.