“A squirt of nigrosine-then dive fast!”
As he spoke, Tom plucked from his belt an explosive plastic cartridge with a tiny plunger at one end. He aimed the cartridge toward the approaching killer whales and pressed the plunger. A high-speed stream of blue-black dye jetted from the front end and spread through the water in an inky cloud.
“Get below, Bud!” Tom ordered.
Flicking their density controls, the hydronauts shot downward to a depth of four hundred feet.
“Now what?” Bud queried.
“Evasive action,” Tom replied. “Follow me!”
For the next few minutes the boys zigzagged back and forth like darting trout, but managed to
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maintain roughly their original northeasterly course. Finally, after a glance at his sonarscope screen, Tom switched off both his drive jet and his sonar pulse and told Bud to do the same for ten minutes.
The boys floated motionless in the murky green depths. At last Tom switched on his sonarscope again, and after studying his screen, signaled all clear.
“Those babies have sharp hearing,” he explained over the sonarphone.
“They would have homed in on us easily if they’d detected any sound-and I’m not sure we could have outrun them.”
“They weren’t as big as most whales I’ve read about,” Bud said.
“Only thirty feet long,” Tom said dryly. “But that ‘killer’ tag is no joke, Bud.
They like to bite chunks out of the bigger whales, and they swallow seals whole.”
“Whew! Let’s be glad we’re not seals!”
“Don’t forget, our special sonar pulse makes us sound like porpoises-and they love those, too.” Tom grinned at the stunned grunt Bud gave. “In fact, they’re one of the largest beasts of prey, and I doubt if they’re very choosy about what kind of meat they go after.”