With the menace of the Iron Mate definitely removed from their thoughts, the crew of the S-18 turned their full attention to the task of retrieving the treasure in the Southern Queen.

Mess that noon was a hasty meal with Commander Ford and the chief divers, Charlie Gill and Russ Graham, taking just time enough to grab a sandwich and gulp a cup of hot coffee.

There was a haze over the mainland and the air was heavy, surcharged with tension. The song of the Isle of the Singing Trees was high pitched and Tim would be glad to see the last of the dismal island.

Plans for the dive down to the hull of the Southern Queen were completed. Members of the crew hurried to their stations, hatches were made fast and the warning bell echoed throughout the interior.

Tim was in the diving compartment. Charlie and Russ had already donned their diving suits and entered the special compartment. Telephone cables, protected by a steel sheeting, ran into the main compartment, giving the divers instant communication with their helpers. Earl Bell was at the phones as chief assistant with Roy Gould standing by.

Commander Ford hurried up.

“Everything all set?” he asked Bell.

“Charlie and Russ are ready and everything in the special diving compartment seems to be all right.”

“Tell them we’re going down.”

Commander Ford hastened back to the control room. From the rear of the S-18 came the hum of the powerful electrics. Tim felt the submarine move slightly. They were going down, going to the bottom of the treacherous bay in search of a fortune in gold, a fortune which had been under water for eleven years.

The special diving compartment in which Charlie and Russ were seated filled with water. Gently the S-18 eased toward the bottom, scarcely more than a foot at a time.

Ten, twenty, thirty, forty feet they went down. Tim watched the gauges fascinated.

The two divers, in their heavily armored suits, sat quietly in their compartment as the pressure increased with the depth.

The 100-foot mark was passed. Still the S-18 was going down. Roy Gould snapped on a switch. Powerful searchlights set in the outer hull especially for this operation cut the blackness of the water. Strange fish blinked their eyes and scuttled away from this monster which was invading the deep.

Now Tim was at one of the quartz windows. In spite of their high power, the searchlights were effective for only a few feet. While he watched the gaunt mast of a ship came upward from the depths. They were descending almost on top of the Southern Queen.

A stubby funnel, rising at a crazy angle, was next, and ahead of that Tim thought he could glimpse the battered bridge.

The motion of the S-18 was almost imperceptible now. The divers, watching the descent closely, were giving orders which Earl Bell relayed on to the control room.

The main deck of the Southern Queen, now heavily encrusted with sea growth, came into view and the S-18 slid lower. There was a gentle bump as it touched the bottom.

Commander Ford came forward and took the telephone from Earl. There was a slight jar as the divers opened the outer door of their compartment and stepped outside the hull of the submarine. Pressure inside their own compartment and that outside had been equalized all of the way down and they were ready to seek an opening into the interior of the treasure ship.

Moving slowly and with each carrying a hand torch, they disappeared beyond the outer rim of light.

It was a tense group in the diving room, clustered around Commander Ford. Tersely he relayed the progress of the divers.

“They’re going back along the hull, hunting for an opening. Charlie Gill says the current is strong here but the footing is hard; probably volcanic rock.”

There was a moment of silence. Electric fans kept a constant flow of air.

Commander Ford spoke again. “They’re still moving back. Wait! Russ Graham’s found a hole, probably the one knocked in the hull when the Southern Queen struck the reef. They’re going inside!”

Every word burned itself into Tim’s memory. It took nerve even to go to the bottom of the ocean, but then to get out of a submarine in a diving suit and walk around the ocean floor and climb into the interior of an old hull took more than nerve.

“They’re not far from the ship’s strong room,” went on Commander Ford, each word low but distinct.

Eagerly they waited for the next message from the interior of the Southern Queen. Would the divers be able to get into the strong room? Would the treasure be there? A dozen questions hammered through the mind of every man aboard the S-18.

Roy Gould checked the even flow of air through the air lines. It was the life blood for the men outside. Once that stopped they wouldn’t have a chance.

Commander Ford bent nearer the mouthpiece of the phone, pressed the headset closer to his ears, straining for the first word of the treasure. His hands were shaking slightly.

Then he turned toward them, his voice hoarse with excitement.

“They’re in the strong room; they’ve found the treasure!”

His words echoed the length of the S-18 and a shout went up from the crew.

“Charlie Gill says someone must have made an attempt to get the treasure out before the Southern Queen sunk. The door of the strong room is open and several of the steel chests are outside the door. They’re bringing them out now.”

Minutes passed as the divers, each carrying a steel chest, made their way out of the interior of the Southern Queen and back along the side of the S-18.

Tim’s keen eyes were the first to see them. Russ Graham was ahead, his arms wrapped around a rusty steel chest. Close behind came Charlie Gill, with a similar chest in his arms. They deposited these in the diving compartment and waved to the men watching them through the quartz windows.

Then they were beyond the circle of light, seeking more treasure in the hold of the old tramp steamer.

“How long can they remain down at this depth?” Tim asked the commander.

“Not long. The pressure is too great, but Charlie and Russ are the best divers in the world. They’ll stick as long as they dare.”

Another and still another trip was made by the divers into the hold of the Southern Queen. The pile of steel boxes mounted. Six were stacked together. There were only two more. Then the job would be done.

Ike Green came running forward from his radio room.

“Something mighty funny is happening near us,” he told Commander Ford. “My microphones are picking up all kinds of noises within the last two minutes.”

A slight tremor ran through the hull of the S-18.

Commander Ford shouted into the telephone.

“Charlie! Russ! Return at once! Don’t attempt to bring out the rest of the gold. Hurry!”

There was another slight movement. Men looked at each other in amazement and fear. Out of the darkness came the divers. Charlie Gill had a treasure chest. Russ Graham’s arms were empty. Into the protection of their diving compartment they stumbled. With a clang the outer doors snapped shut.

“We’re getting back to the surface as soon as possible and away from the hull of the Southern Queen at once,” snapped Commander Ford.

Men hastened back to their posts, but before they could get there, the S-18 moved again. From the outside there was the sound of metal scraping against metal. Then silence.

They took their places, diving planes were adjusted for the ascent and orders flew from Commander Ford’s lips. The electric motors purred smoothly. Compressed air hissed into the ballast tanks, blowing the water out to lighten the submarine. Tim, watching the depth gauge, waited for the needle to move.

Earl Bell came into the control room.

“You might as well shut off the motors and save the air,” he said dully. “That last shock put a part of the hull of the Southern Queen on top of us. We’re trapped.”