"Go ahead, Hal!" he called. "Fifty feet under the surface. Dive
gently."

"O-o-o-oh!" came in little screams of alarm as the guests felt the floor
on which they stood inclining at a sloping angle.

"We're going below the surface now," young Benson informed them. "We'll
soon be running on an even keel."

"All below," called Hal Hastings in a few moments.

"And all clear?" asked Jack.

"All clear, Captain."

"Jack Benson threw aside the heavy curtain, come forward, slowly ladies
and gentlemen, and take seats," was Jack's invitation. "I am sorry I
shall have to ask you all to remain seated, but we cannot have any
serious shifting of weight while we are running under the water."

Though Eph was at the tower wheel Hal Hastings was now virtually in
command of the boat, by previous arrangement, for young Benson meant to
keep a sharp, though covert, eye on passengers.

The young skipper noted, swiftly, that Miss Peddensen had taken the seat
furthest aft in the cabin, while the young Englishman was seated at the
forward end of the party of guests.

"Oh, I say, Captain Benson," called the Englishman, "are you permitted
to show me how you know just how far below the surface you are?"