The strain almost threatened to break that arm, but Dave held grimly, desperately on.
Now he looked about him.

Fortunately there was no growth of seaweed at this point, and he could see clearly for a distance of quite a few yards around him.
"Queer what can have become of the body!" thought Darrin.

"But then, the boat has drifted along slightly, and Miss Butler may have sunk straight down.

She may be lying or floating here just out of my range of vision.

I wish I could let go and strike out, but I'd only shoot up to the surface after a little." Many a shadow in the deep water caused Darrin to start and peer the harder, only to find that he had been deceived.
At that depth the weight of the water pressed dangerously upon his head and in his ears.