. . . . . . .

Del Mar sank, upright and rapidly, down in the shallow water to the bottom.  Once having his feet on something approaching firm ground, he gazed about through the window-like eye of the helmet until he got his bearings.  Then he began to walk heavily along the bottom of the harbor, over sand and rocks.

It was a strange walk that he took, half stumbling, slowly and cumbersomely groping his way like a queer under-water animal.

If any one could have seen him, he would have noted that Del Mar was going toward the base of a huge Focky cliff that jutted far out into the harbor, where the water was deep, a dangerous point, avoided by craft of all kinds.  Far over his head the waves beat on the rocks angrily.  But down there, concealed beneath the surface of the harbor, was a sort of huge arch of stone, through which a comparatively rapid current ran as the tide ebbed and flowed.

Del Mar let himself be carried along with the current which was now running in and thus with comparative ease made his way, still groping, through the arch.  Once under it and a few feet beyond, he deliberately kicked off the leaden-soled shoes and, thus lightened, rose rapidly to the surface of the water.

As he bobbed up, a strange sight met his eyes—­not strange however, to Del Mar.  Above, the rocks formed a huge dome over the water which the tides forced in and out through the secret entrance through which he came.  No other entrance, apparently, except that from the waters of the harbor led to this peculiar den.

Lying quietly moored to the rocky piers lay three submarine boats.  Further back, on a ledge of rocks, blasted out, stood a little building, a sort of office or headquarters.  Near-by was a shed where were kept gas and oil, supplies and ammunition, in fact everything that a submarine might need.

This was the reason for Del Mar’s presence in the neighborhood.  It was the secret submarine harbor of the foreign agents who were operating in America!

Already a sentry, pacing up and down, had seen the bubbles in the water that indicated that some one had come through the archway and was down “below,” as Del Mar and his men called it.

Gazing down the sentry saw the queer helmeted figure float up from the bottom of the pool.  He reached out and helped the figure clamber up out of the water to the ledge on which he stood.  Del Mar saluted, and the sentry returned the secret salute, helping him remove the dripping helmet and suit.

A moment later, in the queer little submarine office, Del Mar had evidently planned to take up the nefarious secret work on which he was engaged.  Several men of a naval and military bearing were seated about a table, already, studying maps and plans and documents of all descriptions.  They did not seem to belong to any nation in particular.  In fact their uniforms, if such they might be called, were of a character to disguise their nationality.  But that they were hostile to the country under which they literally had their hidden retreat, of that there could be no doubt.