Is life really a journey and not a destination? "Under the Whaleback" — a caustic play being given a terrific production by the Wilma Theater — is about a bunch of guys for whom life is solely a journey, because while they're alive, there is no real destination.

They are last century's British and Irish fishermen on the high seas and their journey — catch more fish for fish 'n' chip restaurants, gut them, brave the weather, make the delivery, start all over again — is the sum meaningful total of their lives.

Aaargh!, an old salt might say, Thar's a mighty restricting set-up fer a play! (Old salts are generally correct in these sorts of observations, especially when they say "aaargh" at the beginning.) And I have to agree that even somewhat younger salts may question a play that wanders in aimless discourse through a death-defying storm in one act, then through a violent, dry-land encounter with an irrational person in the next.

For me, the worth of "Under the Whaleback" is not in its plot — I could live without the tediously raw, sometimes funny but often juvenile repartee among the sailors. They're a foursome caught in a miserable storm that rages for days while they huddle in their cabin under the ship's whaleback, a protective area that slopes on both sides to throw off an encroaching ocean by gravity. No food, little to drink, almost no personal space — it's a recipe for raunch.

What drew me to the play is the feeling of confinement and hopelessness it creates in the first act among these frequently unpleasant characters; the compelling mood became far more important and theatrical than the dialogue. So despite itself, "Under the Whaleback" works, at least at the Wilma, where artistic director Blanka Zizka stages it to say everything about the fishermen's lives that the text doesn't.

She has assembled a cast that delivers the play with riptide force and a team of stagecraft artists who deepen the mood as the play moves forward — among them Matt Saunders, whose on-stage ship keels with the strongest wind force, suggested boldly by Daniel Perelstein's sound and Allen Hahn's lighting.

Playwright Richard Bean (he wrote last season's Broadway smash "One Man, Two Guvnors," a wild reconstruction of an 18th-century farce) has provided larger-than-life characters, played here just that way. Veteran actor Pearce Bunting excels in two roles, one being the impetuous, impulsive sailor we're introduced to at the show's beginning.

Brian Radcliffe is convincing as the young sailor who has his eye closest on the staples of a life on land. Keith J. Conallen (also expertly handling two major roles) is the most annoying of the characters, with his swooning cabin fever. Ed Swidey gives us an aloof man who could possibly explode. And for an old and wizened swabbie who's above it all, you can't do better than H. Michael Walls. You can't do better than any of them, steering a wobbly script.

"Under the Whaleback" runs through April 7 at the Wilma Theater, Broad Street near Locust. Tickets: $39-$66. www.wilmatheater.org or 215-546-7824.