Zurita shooed them away: their silvery scales were fairly blinding him. The divers found themselves in a biggish cave, about twelve feet high and twenty feet wide. It was empty, except for the fish apparently sheltering there from the storm or bigger fish.

Treading cautiously they went deeper into the cave. It gradually narrowed. Suddenly Zurita stopped dead. The beam of his torch had picked out from the darkness a stout iron grille blocking their way.

Zurita could not believe his own eyes. He gripped at the iron bars in an attempt to pull the grille open. It didn’t give. After a closer look Zurita realized that it was securely embedded in the hewn-stone walls of the cave and had a built-in lock.

They were faced with still another riddle.

The “sea-devil” had apparently even greater intelligence than they had ever credited him with. He knew how to forge an iron grille to bar the way to his underwater den. But that was utterly impossible! He couldn’t have forged it actually under the water, could he! That meant he didn’t live underwater at all or at least that he went ashore for long stretches of time.

Zurita felt his blood throb in his temples as though he had used up his store of oxygen in those few minutes under water.

He motioned to Baltasar and they went out of the cave, and came up.

The Araucanians who had been on tenterhooks waiting for them were very glad to see them back.

“What do you make of it, Baltasar?” said Zurita after he had taken off his helmet and recovered his breath.

The Araucanian shrugged his shoulders.