There's an undeniable wholesomeness in "The Three Year Swim Club," Lee A. Tonouchi's new play for Honolulu Theater for Youth. And large helpings of innocence and playfulness as well.

The script grew out of oral history and research surrounding Maui swim coach Soichi Sakamoto, who in the 1930s began to train kids in sugar plantation irrigation ditches. The goal was to make them Olympic-ready in just three years.

Everybody likes Cinderella stories and rags-to-riches tales, and the youngsters in this version prove themselves to be Little Engines That Could. Neither does it hurt that the plot is based on true events.

But, curiously, it is not a Sakamoto biographic. When the character of the coach appears, he is always in the background or on the sidelines, and played in turn by each of the four-member cast, who don dark glasses and a straw hat, and pick up a whistle, staff, or clipboard when the time comes.

Significantly, the stars in this drama are the teenage swimmers, which is probably the way Coach Sakamoto always wanted things to be.

Each of the teammates has a distinct personality.

Keo (Junior Tesoro) is the shy, "flying fish," who works harder because of his small size. Fudge (Maile Holk) is the stubborn girl in a household of brothers who torment her over her unfeminine interest in sports. Halo (Jason Quinn) is the braggart, self-appointed lady-killer, and Bill (Moses Goods) is the gifted athlete from Honolulu, who turns to swimming when he is forbidden to play football.

The action line takes this quartet from awkward beginnings to their first big competitive wins. As they gain in confidence, they shed their plantation garb for swim attire, and slowly begin to believe in themselves.

Director Harry Wong III carefully guides the staging between the naturalness of the kids' pidgin banter and presentational elements of choral speaking and story theater — in which actors are both characters and narrators.

He gets wonderful fun out of an impromptu bench-press challenge, in which the kids hang cement-filled paint cans on opposite ends of a broomstick to determine who is the strongest.

The action also neatly segues into competition scenes in which the swimmers are held up by crates or each other as they demonstrate their strokes.

Wisely, the action terminates just as the youngsters begin to touch their real potential, leaving it to the epilogue to wrap up the rest of Coach Sakamoto's career and the lifetime achievements of each of the team members.

Set designer H. Bart McGeehon contributes the suggestion of an irrigation ditch, backed up by rows of sugar cane against a stunning blue sky for an effect that is both realistic and stylized.

Joseph T. Rozmiarek has been reviewing Hawai'i theater since 1973.