Finally the exit passage swelled to a comfortable size. When Elsa joined him, they swam side-by-side against the current, following an upward gradient. The tunnel became larger and larger, the current stronger and stronger. On the other side of a duck-under, they came to a cavernous area about the size of a small house.

Marty checked his dive computer. They were ten minutes past the time they had agreed to turn back. He checked his pressure gauge. He had started with 2800psi in the double steel tanks, and he had already used 1100psi, dipping into his safety reserves.

Even so, they had to be close to where the channel emptied into the ocean. They could push on, surface in the sea, and swim to shore—

No. That wasn’t the plan. They could still get lost, never find the exit, and then they wouldn’t have enough air to return the way they had come.

There was a saying amongst divers that watching your air pressure go down to zero is no way to spend the rest of your life, and he wholeheartedly agreed.

I’ll come back tomorrow, he consoled himself, and the day after that, if need be. I don’t care if it takes weeks or years, I’ll come back every bloody day until I find the creatures.

He twirled his pointer finger in tight circles, indicating to Elsa they were ending the dive. She nodded.

As they were turning around, something large and fast darted past them before disappearing back into the inky abyss.

Chapter 27

Chapter 27

ELSA

Elsa knew they were pushing their luck. They had already added an extra twenty minutes to their maximum bottom time. That meant twenty minutes less reserve air, leaving them a forty-minute safety window. Still plenty of time, but you never knew what emergencies could happen, and even a few minutes of extra air could mean the difference between life and death.

Plan your dive; dive your plan.

It was that simple.

She was about to signal to Marty that they needed to head back when he signaled this to her first. She nodded and was performing a helicopter turn, pivoting on a horizontal axis, when she saw a flash of blue bioluminescent light and a wash of white flesh.

She swung her LED light, trying to track the lightning-quick movement—and saw a powerful, finned tail.

Then it was gone.

Marty began swimming after the creature. Elsa remained frozen in shock.

Was that what she thought it was?

Could it really be…?

She wanted to scream at Marty to come back. Tell him they had to stay together. There was a merfolk in the water with them. But of course she couldn’t do any of that with a respirator in her mouth.

Chapter 28

Chapter 28

MARTY