Undersea Guardians by Ray Bradbury

The ocean slept quietly. There was little movement in its deep green silence. Along the floor of a watery valley some bright flecks of orange color swam: tiny arrowshaped fish. A shark prowled by, gaping its mouth. An octopus reached up lazily with a tentacle, wiggled it at nothing, and settled back dark and quiet.

Fish swam in and around the rusting, torn hulk of a submerged cargo ship, in and out of gaping holes and ripped ports. The legend on the prow said: U. S. S. Atlantic.

It was quite soundless. The water formed around the ship like green gelatin.

And then Conda came, with his recruits.

They were swimming like dreammotes through the wide dark-watered valleys of the ocean; Conda at the head of the school with his red shock of hair flurried upright in a current, and his red bush beard trailed down over the massive rib of his chest. He put out his great arms, clutched water, pulled back, and his long body shot ahead.

The others imitated Conda, and it was very quietly done. The ripple of white arms, cupped hands, the glimmer of quick moving feet, was like the movement of motion pictures from which the sound-track has been cut. Just deep water silence and the mute moves of Conda and his swarm.

Alita came close at his kicking heels. She swam with her sea-green eyes widefixed and her dark hair spilling back over her naked body. Her mouth twisted with some sort of agony to which she could give no words.

Alita felt someone moving at her side. Another, smaller, woman, very thin in her nakedness, with gray hair and a shriveled husk of face that held nothing but weariness. She swam too, and would keep on swimming.