It is mostly music and scenery, though there is some dialogue as well.

The back cover says:

As the last hope of a desperate people, a boy is sent by his elders to retrieve something lost that is of great value to his people. To all people. The only clue he is given is that "The Guardian will show you." With these words, the boy finds himself on the deck of a mysterious sailing ship. There is no crew. He hears only the voice of the ship's spirit, Varua (performed by Academy Award -winning actress Linda Hunt). She offers him the gift of a mystical journey into the natural world. This film addresses the growing awareness of our connection to all life in a stunning celebration of planet Earth... this Third Stone From The Sun.

Filmed from the point of view of the boy, only part of the story is told with dialogue. The greatest part is "felt" through director Jan Nickman's stunning images and the music of six brilliant composers.

Chapter List:

side 1 (CLV)
1. Opening Credits
2. Prelude
3. Children of the Open Sky
4. Between the Earth and the Sky
5. Third Stone From the Sun
6. Oceanus
7. Rains Return
8. Varua
9. One More River Passing
10. Whispers of Light
11. Stolen Fire
12. Walk the Temple

side 2 (CAV)
13. Spirit of the Ice
14. Deep Blue Stranger
15. The Joining Road
16. Closing Credits

According to The Seattle Times, it cost around $5 million to make, while previous albums cost $100,000 to $150,000 to make. The previous ones were just scenery and music. No dialogue, characters, or plot.

The movie on this LaserDisc is preserved on YouTube by the director himself, Jan Nickman. https://youtu.be/P9ceeabXfwI.

The video's description provides more information:

This is a feature film [Jan Nickman] directed in 1990. It was released internationally by Disney in 1991 and a very limited domestic (U.S.) release in 1994 by Miramar. The film won top honors at the Houston International Film Festival, played at the the first annual International Environmental Film Festival in Boulder, Colorado and SIFF (Seattle International Film Festival) among others. Academy Award Winning actor Linda Hunt played the lead role as the voice of the sailing ship Varua.