The tour of the caves comes with a 20-minute boat trip on an underground lake.

The Docks are always constructed on the bank of an underground lake or river.

A feature is an underground lake known as the Mere.

Trying to find a way out, they return to the underground lake.

There is the sound of water dripping in an underground lake.

The river slowed and fed into a small underground lake.

I saw him being carried by a shade into a green light over an underground lake.

Not a sea at all, it was actually an underground lake some five miles long.

He came at last to the huge cavern of the underground lake.

You wouldn't see a big underground lake, as a lot of people think.