Rick grinned. "You're right. But we haven't anything to lose by taking a look, have we?"
They trotted down the beach toward their own house at a half run. Rick looked at his watch. "At least one pair of tanks should be full by now, and there's plenty of time for a dive. Come on!"
They paused at the pier, put the pressure gauge on the first two tanks in series, and found them charged, as Rick had predicted. Then they ran for the house.
Zircon and Tony were gone and there was a note on the living-room table. "We're exploring the southern end. Be back in an hour or two."
"Shall we wait?" Scotty asked.
"No need. We can take our floats. Let's get going."
They changed to trunks. Then, since they would not have anyone on the surface to keep track of time or depth, strapped on wrist watches, compasses, and wrist depth gauges. Floats and weight belts were put on, then the boys added small plastic slates and pencils for writing underwater. Knives, masks, snorkels, their favorite guns, fins, and lungs completed their equipment.
"Shall we walk up the beach, or swim?"
"Swim," Rick said promptly. "This stuff is too heavy to carry comfortably."
They launched floats, placed aqualung mouthpieces on top of their masks, and swam parallel to the beach. By using snorkels they avoided the effort of lifting their faces out of water to breathe and conserved the air in the tanks. With effective but effortless leg strokes they moved along rapidly.