Always the cause of unusual and understandable excitement among the world's showmen is the advent of a feature-length picture bearing the distinguished label, "Walt Disney Presents"--whether the picture flows from the colorful inkwell of the master cartoonist's talented artists, is of his more recent True Life Adventure series or a live-action film. This ultra-modern screen version of Jules Verne's timeless classic is of the last-named category and, probably, is the most eagerly awaited Disneyan adventure since his memorable "Snow White," first of the great full-time pen-and-ink photoplays.

From any perspective of evaluation, "20,000 Leagues" is equipped to become a companion piece to that initialer in both popularity and profits. For here, indeed, is a subject that possesses virtually every element known to be necessary to assure capacity patronage, rave reactions and extended runs. And prominent among those ingredients is the one that has, down through the years, characterized most of the producer's output--an equal appeal to both adult and juvenile spectators.

The masterful screenplay which Earl Felton extracted from the Verne novel adheres rather closely to the original, invading current fields only in a bar-raising climactic sequence that projects implied knowledge of atomic explosives. Startlingly, Felton's scrivening demonstrates that the literary approach to science-fiction thrillers has changed but little since the 1870 appearance of the granddaddy of all such highly imaginative writing.

Kirk Douglas portrays Ned Land, the brash, fun-loving, fearless seafarer who becomes one of the prisoners of dictatorial, visionary Captain Nemo aboard the submarine Nautilus. He brings to the part a breezy, mirth-dotted, tongue-in-cheek delineation, entirely believable and praise-worthy. Sharing acting honors with him is James Mason; as Nemo, he gives an expectedly grim and unbending but effective characterization.

The most prominent stellar facets of the offering are, however, special effects, spectacle, suspense and photography, the last-named in screen-filling CinemaScope and breathtakingly beautiful Technicolor. The technical contributions achieve their pinnacle of highly imaginative excellence in the Nautilus itself--a triumph of planning and design both inside and out. Thrill-freighted are the underwater action sequences, topped by a tensely exciting battle with a giant squid; action a-plenty accompanies the submarine's battles at sea with hostile war ships; and the staging of an attack by ferocious cannibals manages to be both suspenseful and humorous at the same time. Probably most impressive, however, are the closing minutes in which Nemo takes drastic action to ensure that the world shall never learn his secrets.

That the venture, because of its complexities, required a shrewd and knowing directorial hand, is obvious. Richard Fleischer's piloting amply fulfills all demands and results in a solid credit for him.