Discouraged, he wrote on his belt slate, "Mybe no bottm. Flr of cbn my be gne."

Scotty nodded. He lifted his hands in a gesture of inquiry. Now what?

Rick thought about it for a moment. Tony had been right! They probably would have to remove every board in sight, carrying the ship away piece by piece. But then what? There was the distinct possibility that the statue was somewhere under sand, and they had no way of removing the sand to see.

It was apparent that most of the ship was under the sand--if the remainder of the ship was still intact. But Rick couldn't escape the feeling that Captain Campion would have kept the statue close to him.

And that meant in the aft part of the ship, the part that was exposed.

Scotty hooted twice, pointing at his watch. It was time to surface. The next dive would be their last for the day.

On the surface, Rick sounded discouraged as he said, "The cabin we uncovered might not even have a deck. There may be nothing but a mile of sand under it. And there isn't much of the aft part of the ship left to explore, either. I guess tomorrow we can plan to take the captain's cabin apart board by board."

"We'll need Tony and Zircon for hard labor like that," Scotty answered.

"Notice how quickly you get tired down there? Also, we use air a lot faster when we work."

"Let's just sort of make a survey this time," Rick suggested. "We can probe for any cracks we might have missed, and I'll take some over-all shots of the wreck. Then we'll call it a day."

They followed Rick's plan. He took pictures of Scotty, with wrecking bar, prying at likely places in the exposed part of the ship. But Scotty uncovered nothing of interest. In one place his prying disturbed another moray, who demonstrated his anger at the intruders by trying to fasten his needle teeth in the wrecking bar.

A metallic clang caused them to lose interest in the eel suddenly. They looked at each other, then turned and swam toward the apparent direction of the sound. At that moment a distant wail struck their ears.

The bra.s.s ball!

Rick wondered. He had heard no boat noise. The bra.s.s ball must be operating automatically. He hooted for Scotty's attention, then pointed toward the cave.

Scotty checked his spear gun and motioned for Rick to lead. Rick pushed his camera in front of him and made his fins move rapidly. There might be some outward sign when the ball sounded, something that would tell them a little about its mechanism or purpose.

As the cave came in view he coasted, looking upward. The murky layer prevented his seeing very far, but there was no one in sight. He let inertia carry him toward the cave, then swung upright in the water as he saw that the octopus had moved a little distance from the cave mouth.

Instinctively Rick knew that something was wrong, but it was too late to get out of harm's way.

A frogman emerged from the cave, spring-type spear gun pointed directly toward them. The frogman held the bra.s.s instrument in his free hand.

Even as Rick hooted a warning, the frogman fired!

His spear lanced through the water directly at Scotty!

CHAPTER XVII

Trapped in Twenty Fathoms

Scotty writhed to one side, and the fact that the frogman had fired from too great a distance gave him time to dodge. The spear went by, and Scotty lifted his own gun to return the shot.

Rick, senses suddenly acute, glanced upward again in time to see two more figures descending through the murky layer. He hooted for danger!

Scotty glanced up, too. Then, instead of firing, he sped forward and thrust the tip of his spear at the frogman's chest. The frogman lifted his hands high. Scotty jerked the man's face plate loose, then turned swiftly and motioned to Rick.

Rick followed, fins driving, as Scotty led the way into deeper water in the direction of the wreck.

The frogman who had been in the cave was temporarily out of things. His Scuba was the type that combined the breathing apparatus with the full face plate. He could clear the face plate of the water Scotty had let in, but it would take a little time.

Suddenly Scotty shot upward. Rick turned and looked over his shoulder as he followed. The second two frogmen were in clear water now, and both had spear guns!

Scotty led the way into the murky layer, then leveled off and swam horizontally. Rick wondered what kind of evasive action his pal was planning, but he followed without trying to communicate with the other boy. In a situation like this, Scotty's instincts were dependable.

Rick stayed close to Scotty in the murky layer, swimming at his side and a little behind. After a few yards Scotty dove again, into clear water.

Rick looked around but could see no sign of the enemy. Apparently the frogmen had followed and were still in the murk.

Scotty shot downward, Rick at his side. The wreck was directly below them. Scotty didn't hesitate. He let his momentum carry him right through the grouper's front door into the cabin. Rick followed, half expecting to see Scotty and the grouper meet head on, but the fish hadn't returned.

Inside the cabin, Scotty switched on his flashlight, took his slate, and wrote, "Thyl thnk we wnt bk to bot. We sty hr lng nuff thy fnd out we nt thr & cm bck lkng fr us. Thn we go up to bot."

Rick nodded his understanding. It was good strategy, provided they timed it right. The frogmen would a.s.sume the boys had returned to the _Water Witch_ when they went up through the murky layer. They would examine the boat, then dive down again. At that time, if he and Scotty could time it right, the two groups would pa.s.s in the murky layer and the boys would emerge while their enemies were still descending.

He looked at his watch. They had only a few minutes of air left. The frogmen would have more air, not only because they had entered the water after the boys were already on the bottom, but because they had not descended so deeply.

He wrote, "Rlax. Brethe easy."

The less effort they made, the longer their air would last. For a moment he debated suggesting that they share one tank by trading the mouthpiece back and forth, but that would leave one of them practically without air when they had to leave. He tried to imagine the movements of their enemies. The frogmen would be on the surface now, approaching the boat ladder with caution. They couldn't be sure the boys were not waiting in ambush.

Both boys had switched off their lights and were resting motionless in the darkness of the cabin. A little light filtered through the hole near the roof, but not enough to see by.

Suddenly the light was blocked out!

Rick reached for his belt knife and Scotty thrust the spear gun forward, then both relaxed a little. The grouper had returned.

The big fish turned at the opening and backed into his hole. He hovered in the opening, holding position while he stared out into his watery kingdom. Apparently the fish had no idea that the boys were in the cabin. When it came time to leave and they touched him or hooted at him, he would get the surprise of his life.

Even in their predicament, Rick could see the humor in the grouper's reaction. He wondered if groupers were subject to heart failure from shock.

Rick returned to trying to imagine the movements of the frogmen. Now they would be cautiously boarding the _Water Witch_, one up the ladder, the other climbing the anchor chain. They would be careful, still unsure whether or not the quarry was aboard.

He thought he felt constriction in his lungs from the warning signal that his air was running out, but finally decided it was only his imagination.

Now the frogmen would be aboard the _Water Witch_, making a quick search, spear guns ready to fire their lethal shafts. Now they would be in the cabin and shouting their disappointment.

Now the frogmen would be hurrying back into the water, readjusting their face masks, ready to dive.

The grouper shot out of the cabin with a flick of his powerful tail that raised the silt around them.

Rick's heartbeat faltered. The grouper had been alarmed. They had mistimed!

Right now, the frogmen were outside the _Maiden Hand_!