YOU CAN'T PICK UP the papers anymore without reading something new about the bounty the seas keep offering us, things we never expected, life which sustains itself without sunlight but rather with the heat and chemicals bubbling up from the earth's core, sea slugs which all but remind you of your Uncle Art, the ugly one. The oceans are particularly in, more mysterious than space (if not comparable, perhaps, to the manmade enigma of Stonehenge) and almost certainly more useful to man. There's a lot of weird stuff down there, folks, and two veteran chroniclers of aquatic goings on are on hand for the summer with new novels. The only bond, other than their respect for sea creatures, which unites Peter Benchley and Hank Searls is the fact that the former wrote Jaws and the latter had the assignment of cranking out Jaws II. One might assume from that tidbit of what is essentially movie lore that Searls is a hack, a typewriter- for-hire. One would, as it happens, be wrong.

Searls' novel, Sounding, concerns a couple of weeks in the life of a 59-year old, 70-ton, sperm whale who is a good deal more intelligent than you or I, more sensitive, more reflective, infinitely more biologically sophisticated, and rather worried that he may have reached the end of his rope. He contemplates his death, when his great body will "join the feeding chain" and his mind will find its way to "the Ocean of Thought." I'm not doing this creature justice: he's the most likeable fellow you're likely to meet in a novel this season, sort of a cross between Jimmy Stewart and Henry Fonda and William Holden heading for the last shootout. And if you don't reflexively gag on anthropomorphic fiction, you'll find this the best example of the genre since Watership Down.

Sounding is also possessed of a simple, decent theme, running pretty much along the lines of salvation lying in the hope of all earth's creatures acknowledging their interdependence. Not exactly original, perhaps, but warmongers have won the Nobel Peace Prize for less, and Searls is remarkably eloquent on the subject. His eloquence runs less to stylistic touches, more to elaborate compilations of facts fortuitously arranged to demonstrate his thesis. You'd have to know a hell of a lot more about whales and other sea creatures than I do not to learn a great deal in the most enjoyable fashion imaginable. For instance: "He had a brain biologically identical to man's but seven times its weight and volume. His kind had already possessed it for thirty million years when man's microcephalic ancestors tottered from African forests onto the savannas of the veldt." It is the largest brain the planet Earth has ever known and Searls suggests the power of its sonar scanning system: coming across a giant squid the whale ascertains by sonar what the squid has recently dined upon (the contents of the stomach, you see) before continuing the food chain by dining upon the squid.

Trust me, this is good work, good enough to make you pass over the sunken Russian sub, the cast of characters aboard, and the prospects of the heroic whale somehow saving them. Read Sounding for the whale, for Searls' encyclopedic knowledge of this greatest of creatures and its habitat, for the similarity he finds between man, who began as a sea being and chose the land to make his home, and the mighty whales, who also began in the sea and gave the land a try but decided so long ago to go back to the almost boundless riches of the sea. Incidentally, if you're a crybaby like me, don't worry about the end of the story: You'll stand up and cheer.

Peter Benchley's The Girl of the Sea of Cortez (a much shorter book than Sounding though the pagination might make you think otherwise) is something else again. Having written the startlingly suspenseful Jaws, the mawkish adventure of sunken treasure, The Deep, and the mindlessly sadistic gore of The Island, Benchley has decided it's time for a kind of amphibian Love Story, the principals here being a teenage girl, a child of nature Gauguin might have gone bananas wanting to capture in all her primitive innocence, flowers in her hair and whatnot, and a gigantic manta ray she rescues from a man-inflicted wound.

When Benchley sticks to the manta ray, the girl, and her memories of her late father who instilled in her his love and respect for the sea and its inhabitants, he is often effective, even poignant, moving. But out of water he is quickly beached and gasping his last. The problem is the plot, an unnecessary, intrusive story about the girl's younger brother who is a monstrously evil git, a blackhearted fisherman, despoiler of all he touches, a coward and a rotter, definitely a throwback to the icky pirates of The Island. Would they had gotten their hands on him before this brief novel had gotten underway. However, we're stuck with him and his ghastly chums. He tries to kill his sister, succeeds in doing in a great many fish without the slightest ecological conscience, and . . . well, the hell with him. The result of all this is a sort of Disney film on paper, which is too bad because the fable of the girl and the manta ray might have made a nice novella for young-teens. As it stands, it's just another thriller for young-teens with some vaguely Hemingwayesque The Old Man and the Sea touches which the very young, or the very gullible, might confuse with art of the Jonathan Livingston Seagull school.