Tolland's lungs ached for air and yet he stayed right there with her. Every time Rachel pounded on the glass, Tolland heard air bubbles gurgling up and the sub sank deeper. Rachel was yelling something about water coming in around the window.
The viewing window was leaking.
A bullet hole in the window? It seemed doubtful. His lungs ready to burst, Tolland prepared to surface. As he palmed upward across the huge acrylic window, his fingers hit a piece of loose rubber caulking. A peripheral seal had apparently been jarred in the fall. This was the reason the cockpit was leaking. More bad news.
Clambering to the surface, Tolland sucked in three deep breaths, trying to clear his thoughts. Water flowing into the cockpit would only accelerate the Triton's descent. The sub was already five feet underwater, and Tolland could barely touch it with his feet. He could feel Rachel pounding desperately on the hull.
Tolland could think of only one thing to do. If he dove down to the Triton's engine box and located the high-pressure air cylinder, he could use it to blow the negative ballast tank. Although blowing the damaged tank would be an exercise in futility, it might keep the Triton near the surface for another minute or so before the perforated tanks flooded again.
Then what?
With no other immediate option, Tolland prepared to dive. Pulling in an exceptionally deep breath, he expanded his lungs well beyond their natural state, almost to the point of pain. More lung capacity. More oxygen. Longer dive. But as he felt his lungs expand, pressuring his rib cage, a strange thought hit him.
What if he increased the pressure inside the sub? The viewing dome had a damaged seal. Maybe if Tolland could increase the pressure inside the cockpit, he could blow the entire viewing dome off the sub and get Rachel out.
He exhaled his breath, treading water on the surface a moment, trying to picture the feasibility. It was perfectly logical, wasn't it? After all, a submarine was built to be strong in only one direction. They had to withstand enormous pressure from the outside, but almost none from within.