Into the Glowing Depths

From the back cover:

A menace awakens in the irradiated ocean depths of Terra A.D., one desiring the conquest of the lands above. Standing between an army of mutant genetic experiments and world domination is an isolated research facility miles beneath the ocean's surface. From within that remnant of the ancient times, a most unusual intelligence seeks heroes to act on its behalf. The characters soon find themselves in a hostile environment, beset by enemies on all sides, but with rich rewards awaiting them if they can prevent the mutant army's conquest. Will they succeed in thwarting an evil spawned in the glowing depths of the post-apocalyptic future or will they breathe their last breath deep, deep under the sea.