He bent his ear keenly. A soft drip-drip sounded just beyond the rail. Then a black hand glistening with water clutched the rail itself.
Slowly, cautiously the body of a dusky native, attired only in swimming garb, came into view. This was the person Dave had detected swimming under water.
Straddling the rail, the intruder crouched, looking all about the deck. Then he lifted both feet over onto the planking.
Dave now noticed that the man carried under one arm quite a bulky package done up in black oilskin.
The intruder glanced sharply at the forecastle. Just abutting it was a box-like section into which all kinds of odds and ends of canvas and ropes were bundled. Its door was half-ajar. Dave saw the stranger glide to this, thrust his package inside, glide back to the rail, slip over it, and drop into the water.
A minute later the ripples in the creek showed where the fellow was making his retreat under water. His head came up to the surface once or twice. Then he arose at a distance down the stream and disappeared among the dense shrubbery lining the creek.
"More mischief," instantly decided Dave Fearless.
Dave made a rush for the forecastle cubby hole. He pulled its door wide open and groped about. His fingers closed about a dripping object there.
"Hard and heavy," said Dave. "Wrapped in the oilskin to protect it. What can it be?"
Dave arose to his feet. Suddenly a thrill passed through his frame.