“But there’s an island almost in line with two of the lower ones that wasn’t on the map,” objected Tom.
“Anyway, here’s a good channel, and we’re going South again—back toward where we started,” Nicky argued. “Let’s——”
“Back water! Back water!” ordered Cliff. But they had given a swift impetus to the small craft as Nicky and Tom bent to the oars and with a dull grating sound the bow up-ended a little, as it ran onto a shelf of the bedrock limestone, into which the coral formed itself.
Tom and Nicky narrowly escaped toppling over backward and Cliff saved himself from a plunge onto the shoal only by gripping the thwart with both hands as the boat stopped sharply.
“Well—here we are!” said Nicky, settling himself. “Come aft, Cliff, so we can lighten her bow and maybe we can pole off and back out—it’s too narrow a channel to turn around in!”
Cliff stood up to do as his chum counseled; but he remained standing, his eyes fixed, his body becoming tense.
“What’s the matter?” cried Nicky. “See anything?” asked Tom.
Cliff lifted a hand, pointing dramatically.
“Come here Nicky—Tom!” he urged. “Easy, so as not to tip the boat! Do you know what? That is the Dipper, and we have run aground right where the line would show we ought to stop in the chart—and yonder is ‘the bottom of the Dipper!’”
Excitedly his fellows scrambled over the intervening seat and crouched at his side.
“That’s right, I do believe!” agreed Nicky. “The reason the line stopped is because the channel stopped. This is where they must have come to a standstill in the old boat—those castaways!”
“Yes,” added Cliff, “they couldn’t go any further. And the bottom is level here. We could climb out and walk along it.”
“It’s just the place to unload chests of treasure,” Tom agreed. “If only there was some place to hide it in——”
“What about that?” cried Nicky, pointing straight ahead. “There on that islet that’s really at the bottom of the Dipper.”
“But it said ‘in’ not ‘at’ the bottom of the Dipper,” reminded Tom. Nicky nodded, scrambling out into the shallow water. Cliff followed, and Tom delayed only long enough to draw the nose of their tender far enough onto the shelf of limestone to prevent any chance of a slight current drifting it out of easy reach while they walked along carefully on the coral bed, avoiding jutting prongs and dodging the menacing little spaces into which a foot could slip so as to twist an ankle.