prisoners.

After journeying in this way for about two miles they came unexpectedly
(to them--for of course Simon the guide knew where he was leading the
party) upon a circular opening among the hills, beneath which was what
appeared to be a table land of dark earth or peat.

"A swamp," said Harry Girdwood.

"It looks like a bog," said young Jack, "but yet I can see something
moving."

"It is water."

"A lake."

"Yes."

"How black--how dismal it looks."

It did, indeed.

Silent and gloomy, like a table of metal, spread the darkling waters of
this strange lake.

Wild and desolate was it in the extreme.

On every side it was enclosed by towering heights, bare, treeless and
solemn.