"They must be using lungs," Scotty said. "Watch for bubbles."
No bubbles were visible, either. Rick checked carefully and began to worry. It was a calm day with little wave action, and the bubbles from the lungs should have been clearly visible. Surely they wouldn't swim so far the bubbles couldn't be seen on a day like this.
"Let's check," Rick said.
The boys hurried to the room where the Scuba equipment was kept. Two lungs and the blue and white equipment were gone. So was the cart. A quick look at Pirate's Cove showed no cart in sight.
Where could they have gone? The boys hurried to the front of the lab building again and found Joe Blake still getting a bit of sunshine.
"Did you see the girls?" Rick asked hurriedly.
Joe nodded. He motioned across the island. "They came and got aqualungs and hauled the cart across to the north side. They're probably swimming over there."
Rick doubted it. He doubted it very much. The currents on the north side kept the bottom stirred up and visibility was too poor for diving.
Without the need of exchanging a word, Rick and Scotty were suddenly running. As they passed the house Rick had a sudden thought. He went in and ran up the stairs to his room, grabbed his radio unit and turned it on.