Matt was cool enough, but his words were startling.
"How can ve do dot?" returned Carl.
"By boarding the submarine and getting busy," Matt replied.
"Jurgens must have several men there, Matt," said Dick.
"They're probably looking after Townsend's three men. If we can release Cassidy, Burke and Harris, our force will be plenty large enough to take care of this gang of ruffians."
Although it was impossible for either Jurgens or Whistler to move or speak, yet they could hear well enough, and the work Matt was suggesting to his friends caused them to mumble behind their gags and to writhe about angrily.
"If we win," went on Matt, briskly, "we've got to hurry. Come on, pards," and he flung out of the tent and raced down the beach.
There was no one in sight about the Grampus. The cover of the conning tower was still pushed back, but it was clear to Matt and his chums that the rest of Jurgens' men were busy below.
Quickly, and with as little noise as possible, Matt, Dick and Carl waded out to the Grampus. Matt was first to reach the ladder at the bow, and he swung up it lightly, crossed the deck and climbed into the conning tower.
An iron ladder afforded him means for descent into the hull of the boat, and the lunettes, or little windows, in the sides of the tower lighted his way downward.