The sinister object had evidently been under water for years. Its globular shape was thickly encrusted with barnacles and seaweed. Only a small portion of it was above the surface, but even that relatively diminutive part displayed a pair of aggressive-looking horns. These, composed of brittle material, had only to be fractured and the explosive contents of the mine would be detonated. "Right in the fairway," remarked Peter. "Yes," agreed the Scoutmaster. "Right in the line of shipping. It's up to us, lads, to do our best to scotch it. Carline and Phillips! You two keep aft and watch that mine. Don't lose its position whatever you do! Now, lads, down spinnaker! Smartly, now!" The huge light triangular sail was lowered and unbent in double-quick time, and the spinnaker-boom topped-up into its usual place. "Down helm!" ordered Mr. Grant. "Mainsheet home! Stand by headsheets!" The _Puffin_ came round slowly yet surely into the wind, close-hauled on the starboard tack. "How does the mine bear?" asked the Scoutmaster. "Two points on our starboard bow, sir," replied Carline. "Good!" continued Mr. Grant. "Now, lads, listen! We've got to buoy that mine. We can't tow it. That's too risky, because the thing might go up and us with it. On the other hand it might not, since it's probably been under water for eight or nine years. Last week's gale parted it from its moorings, I should imagine. Lee-o! We'll beat up to it as close as we dare." As soon as the _Puffin_ had settled on the other tack, Mr. Grant continued:-- "Get up one of our water-beakers and empty it, Brandon. You, Talbot, get Letter B flag from the signal locker, and lash it to the boathook staff. Now, Peter, you're a splendid swimmer. Are you willing to run a possible risk? Good, you are! Off with your things, then. You and I are going for a swim." Scoutmaster and scout began to divest themselves of their clothing. Meanwhile the boathook staff with the red swallow-tail flag attached, had been thrust into the bung-hole of the now empty beaker. A length of stout rope was bent to the barrel and coiled up ready for further use. The _Puffin_ was now hove-to at about fifty yards from the drifting mine. Mr. Grant and Craddock dived overboard. The beaker was dropped into the water, and the two swimmers, towing their make-shift mark-buoy, made for the mine. "Near enough!" announced the Scoutmaster. "Keep the buoy as she is, Peter. Don't let it bump alongside, whatever you do. I'm going to dive." Taking the slack of the rope, Mr. Grant approached to within a few feet of the mine, and disappeared from view. Ahead, and at about six feet underneath the sinister object, he saw what he hoped would be there--a length of rusty iron chain secured to a ring at the base of the mine. Working rapidly, yet with extreme caution, he bent the end of the line to one of the links of the chain; then, striking out until he was well clear of that barnacle-encrusted menace, he broke surface.