The Metropolitan Opera's production of "Tannhauser" with which the 94th season opened on Monday night, is one of the most beautiful visual experiences to be seen on any opera stage today. New last year, it is the work of designer Gunther Schneider-Siemssen, who with lighting designer Gil Wechsler has succeeded in creating illusions of beauty in muted colors that provide exactly the backgrounds called for in Wagner's explicit instructions.

"Tannhasuser" is the second of Wagner's operas in which he deals with the problem which was to fill every succeeding one - the problem of man's salvation through the intervention of woman. In "Tannhauser," the hero is torn between his violent physical passion for Venus, the love goddess, and his pure spiritual love for Elisabeth, the niece of the ruler of the region of Germany in which the legendary opera is set. Tannhauser's final salvation is achieved only when Elisabeth dies, her final prayers being for his soul.

It is hard to recall any stage set more compelling than the picture of the Venusberg, the fabled home of Venus, with which the opera opens. Distant waterfalls create a mist that rides and recedes throughout the course of the bacchanale, for which choreographer Norbert Vesak has devised some of the most effective dance ever seen on the Met stage.

It would be difficult to over-praise the artistic totality of this scene, which is one of the most difficult to realize in all opera. Rightly enough, the principal inspiration for all that happens is Wagner's sensuous score in its later, Paris revision. Written after he had completed "Tristan," the music touches the same erotic notes as those of the later work. So completely had Wagner become imbued with his new style that it is a decided wrench, at the end of the Venusberg music, to hear him return to the rather square manner in which the greater part of "Tannhauser" is written.

If the visual aspects of the new production linger vividly in the memory, it's musical triumphs were, with one notable exception, equally impressive. James Levine, the company's musical director, conducted the lengthy opera with a keen awareness of the need to keep moving at various signal points. Without any sense of undue haste, he propelled his strong cast from scene to scene in ways that highlighted everything that is important, and minimized as much as possible those stretches that approach the doldrums. The orchestra was in glorious shape, making the most of the frequent contrasts in the instrumental writing.

For grand exuberance, nothing else in the opera equaled the splendor of the entrance of the guests into the hall of song. Here, with unusual generosity, eight on-stage trumpets glorified the whole passage. The Metropolitan's chorus, which has been improving steadily in recent years, carried off its assignment in great style, and here especially, the stage management of Phebe Berkowitz seemed exactly right.

Except for the title role, each of the principals was outstanding. Teresa Zylis-Gara is a radiant Elisabeth, as much so in voice as in her lovely appearance. Her greeting to the hall of song was thrilling, and her final prayer deeply touching. There is nothing she could accomplish with her vocalism that is not handsomely present. Tatiana Troyanos, singing her first Metropolitan Venus, sounded as seductive as she is supposed to. And she looked the part so convincingly that it is hard to imagine quite why Tannhauser left her high-class establishment.

Bernd Weikl, the young baritone who made his Met debut as Wolfram last season repeated his success in the role. He sings with the distinction of a great Lieder artist, making every word clear and phrasing every scene in tones of elegance. Kurt Moll bowed in at the Met as the landgrave. His voice, which is familiar from recordings, is rich in texture and of the right weight, while his style was admirable.

It is only in the title role that the cast suffers seriously. Richard Cassilly, who was scheduled to sing the part later in the season, sang on opening night because James McCracken canceled his entire Metropolitan season in a huff over television casting. Unfortunately, Cassilly's voice has, over the years, deteriorated to the point where it is all too often little more than unpleasantly nasal and reedy. It made the Rome Narrative in the final scene an undue hardship. The opera world sorely needs a handsome, young Tannhauser, but they are hard to find these days.

On the whole, however, the performance was carried off on an unusually high level. As a visual spectacle it is one of the Metropolitan's greatest accomplishments.