No one can say that Brooke Shields isn't deep. In her TV movie debut, "Wet Gold," airing tomorrow at 9 p.m. on Channel 7, Shields goes overboard and underwater as an actress in a tropical tale of gold, greed and lust, stirring up sailors and competing with Cousteau-esque footage of incredible sea creatures.

You don't need a compass to figure out where this creaky, leaky vessel is leading. Girl gets guy, girl gets gold, girl loses guy, etc. Shields and whatever mates survive will learn that even billions in bullion and a body by Nautilus can't buy happiness.

As long as her sentences are short ones, Shields does a creditable job, even with this silly, soggy script. She plays Laura, a waterfront waitress who up and quits her job and goes off to salvage a long-forgotten cache of sunken gold, picking as her unlikely partner a croupy old salt, played with wheezy gusto by Burgess Meredith. But though she's really trying hard ("I'm tired of being a joke," she emotes at one point), it's never quite possible to believe in her as anything other than a mermodel.

The rest of the crew is so much decorative driftwood. Laura's pouty, paranoid boyfriend Chris is played by Tom Byrd, a startling Shields lookalike, down to the matching cleft chin. This poor little rich kid goes into a jealous snit whenever mercenary diver Keating (Brian Kerwin) sneaks a sidelong leer at Our Miss Brooke.

That happens more often than not -- in fact, nearly every land and sea creature in sight makes a pass at Shields, including a rather diminutive shark. The vision of siren Shields oiling up and lolling on deck precipitates the inevitable battle of the male models. The whole selfish, shallow bunch devotes most of their slim conversation time to what they want out of life, which is always something they can buy.

Of course, plot and complications are incidental to this movie's real purpose. The finding of the gold is anticlimactic -- the real treasure is the trunkful of swimsuits (I counted eight) that house Shields' ship-shape and sturdy shoulders. To their credit, the scrupulously egalitarian filmmakers make sure the boys are seen in bathing suits and towels as often as Shields -- even Meredith gets a wet T-shirt scene. But for all the shiny skin, there's little real steam generated -- in her love scenes, Shields doth protest too much.

But enough nitpicking. Although most of the adventure scenes have been pirated from other underwater epics -- with two variations on the icky skeleton scare from "Jaws" -- there's a drop more tension than can be found on the Love Boat. Filmed on location in the Bahamas, with a lush look and a languid pace, "Wet Gold" is entertaining despite itself.