Ice Station by Matthew Reilly

Antarctica is the last unconquered continent, a murderous expanse of howling winds, blinding whiteouts and deadly crevasses. On one edge of Antarctica is Wilkes Station. Beneath Wilkes Station is the gate to hell itself...

A team of U.S. divers, exploring three thousand feet beneath the ice shelf has vanished. Sending out an SOS, Wilkes draws a rapid deployment team of Marines-and someone else...

First comes a horrific firefight. Then comes a plunge into a drowning pool filled with killer whales. Next comes the hard part, as a handful of survivors begin an electrifying, red-hot, non-stop battle of survival across the continent and against wave after wave of elite military assassins-who've all come for one thing: a secret buried deep beneath the ice...