though.”

“That would be interesting,” agreed Frank, “I’d love to go down in a diving suit and walk about on the bottom. Don’t the fish and things ever trouble him?”

“No,” responded the purser, “even sharks keep off—only danger’s in devil fish—octopus, you know. They grow mighty big hereabouts and are likely to grab anything. Rawlins was making one picture of a whopping big octopus fighting with a diver—fake devil fish made out of rubber, but natural as is. Don’t know how it turned out but I tell you I’m not keen on running foul of any of the real thing. And speaking of sharks—say, here’s a fact that you boys will think’s a whopper. Niggers down here dive in right among the sharks—carry a long knife in their teeth—and grab hold of a shark’s fin and knife him, fact!”

“Well, you can’t tell any yarn bigger than that!” laughed Frank. “Imagine a man tackling a shark under water! Oh come, you must think we’re easy!”

“Well, just wait and see,” replied the purser, “but I’ll have to be running along. There’s New Providence ahead—we’ll be getting into port within the next hour.”

“Gosh, he’s some talker!” exclaimed Tom with a laugh when the loquacious officer had left. “And wasn’t it rich—his telling us about Rawlins and the suits and never guessing we knew him or had been down in those suits ourselves! Say, I’m beginning to think there’s a lot of fun in being Secret Service people. It’s sport listening to folks telling all they know about a thing that you know more about and they never guessing it.”

“Yes,” agreed Frank, “and I can understand now how detectives and Secret Service men find out so much without any one suspecting them. They just start a conversation and then let the other fellows do the talking and pick up a lot of information. But that was rich about the sharks!”

“And the devil fish too!” added Tom. “Wonder if there is any danger from being attacked by an octopus. Say, if there is that’s where our undersea radio would come in mighty fine.”

But whether or not the purser’s tales were true in regard to the sharks and octopus the boys soon discovered that he had not in the least exaggerated the clarity of the water or the skill of the native diving boys when their ship steamed slowly into Nassau harbor.

It was all so wonderfully fascinating and beautiful that the boys kept constantly uttering exclamations of surprise and delight. Never had they dreamed that there could be such vivid colors anywhere in the world. The sky, so blue it resembled a dense solid dome of blue silk; the water, ultramarine, emerald and turquoise streaked with gold and purple; the vivid green foliage with masses of scarlet hibiscus and flaming poinciana trees; the glaring, snow-white coral streets; the pink, blue, green, yellow, and lavender houses with their red roofs and green shutters; the bright-hued orange and red bandannas and gleaming costumes of the negro women crowding the dock; the lofty nodding palm trees above the beaches and looming like gigantic feather dusters above the buildings; the crimson and blue flags of England flying everywhere; the scarlet tunics of strolling soldiers from the garrison; the little shore boats bobbing upon the water and painted every color of the rainbow and scores of sponging and fishing smacks as brilliant in hues as the smaller craft, all combined to form a kaleidoscopic picture of gaudy tints and blazing colors such as can be found only in the tropic islands of the Caribbean. But all these sights were of less interest to Tom and Frank than the naked black, brown and yellow diving boys who paddled about the ship in crude home-made boats, formed from discarded packing cases, or straddled lengths of bamboo and with grinning faces and rolling eyes begged the passengers to throw coins into the water exactly as the purser had described. And when Tom and Frank tossed shining nickels into the sea and the score of black bodies left the makeshift boats as one, the two American boys burst into roars of merriment.

“Gosh, they’re just like a lot of black frogs!” cried Tom. “And just look at them, Frank! See them! Look there! They’re after those nickels and you can see them as plain as if they were under glass! There! Look! One of them’s got a coin! And see how funny the pink soles of their feet look! Say, it’s wonderful!”

For the next half hour the diving boys reaped a rich harvest of small coins and then, the customs and port doctor’s men having completed their inspection, Tom and Frank followed Mr. Pauling down the gangway and a few moments later stood upon the first West Indian island they had ever visited.

CHAPTER II—A MYSTERIOUS DISAPPEARANCE

For the first few days of their stay in Nassau the boys found plenty to amuse them. They rowed out in a bright-hued rowboat with a glass set in the bottom and gazed at the famed “sea gardens” and found them even more wonderful than the ship’s purser had described. They clambered over the ancient forts Williams and George; they bathed, swam and fished to their hearts’ content and they visited the sponge docks where the speedy little schooners and sloops with their grinning black crews brought their catch of sponges to barter and trade.

The huge turtles, lying on their backs upon the decks of fishing boats, were a novelty to the boys and they were absolutely fascinated by the rainbow-tinted fish that swarmed in the waters and were sold in the market. And they learned many new and interesting things also. They had seen the bleached white corals in museums and saw the same everywhere for sale in Nassau; and the first time they visited the sea gardens and gazed down through the crystal clear water they were surprised that no corals were visible.

There were huge sea-fans—purple and golden brown, long, black sea-rods, brown and purple sea plumes, huge dull-orange and maroon starfish, innumerable sea anemones with immensely long and bright-colored tentacles and everywhere red, pink, yellow, blue and particolored fish, like some sort of exotic butterflies, flitting lazily among the marine growths. But not a white coral was visible. Great rounded mounds of orange, bits of scarlet, masses of green and lavender, of old rose and soft fawn brown were cluttered upon the bottom, but in vain the boys sought for the massive brain corals and graceful branched corals they knew so well.

“Well I don’t see any corals,” declared Tom after he had gazed at the multicolored objects upon the ocean bottom for some time. “It’s pretty, but I thought corals grew everywhere down here.”

The black boatmen chuckled. “Beggin’ yo’ pardon, Chief,” he remarked, “tha’s plenty coral down tha’, Chief. Yaas, sir, all erbout. Doan’ yo’ di’sarn ’em, Chief?”

“No,” replied Tom, “I can’t see a single white thing there—all I see are bright colored weeds and sea-fans and rocks.”

The negro looked genuinely surprised. “Bless yo’ soul!” he exclaimed. “Yo’ cawnt be a s’archin’ fo’ white coral is yo’? White coral’s jus’ dead coral, Chief. Tha’s da culmination o’ tha’ manner o’ it’s prep’ration, Chief. Yaas, sir, all tha’ objec’s yo’ di’sarn growin’ down to tha’ bottom is corals, Chief. Yaas, sir, some of tha’ kin’s is yellow an’ some red an’ some green.”

It was the boys’ turn to be surprised. “Why, you don’t mean all those things like stones covered with bright-colored weeds are coral!” exclaimed Frank incredulously.

“Yaas, sir, Chief,” the negro assured him. “Ah’ll demonstrate it to yo’ entire satisfaction, Chief.”

As he spoke, the half-naked negro stood up in the little craft and before the astonished boys realized what he was about to do he had plunged into the clear water and the boys watched in wonder as they saw him swimming easily straight towards the bottom, a little string of bubbles rising from