An akoonah was a device used by some Native Americans in the 24th century to facilitate vision quests, taking the place of psychoactive herbs used by their ancestors. It was used by placing one's hand on the surface of the device and concentrating on an object important to the user.
Commander Chakotay's medicine bundle consisted of a blackbird's wing, a river stone bearing a CHAH-mooz-ee, and an akoonah. In 2371, he showed Captain Kathryn Janeway how to use the akoonah so that she could seek her animal guide. (VOY: "The Cloud")
In 2372, believing that Seska had impregnated herself with his DNA and given birth to their son, Chakotay used the akoonah to seek the spirit of his father, Kolopak, for guidance. His father advised him to embrace the child instead of denying and punishing it for the crimes of his mother. (VOY: "Basics, Part I")
Neelix asked Chakotay for the use of his akoonah in 2374, following a near-death experience after which he found himself in a deep existential and spiritual crisis, questioning his long held beliefs in the afterlife. (VOY: "Mortal Coil")
In 2375, Chakotay used the akoonah to investigate the hallucinations he experienced after the USS Voyager became trapped in chaotic space. The vision quest allowed lifeforms native to chaotic space to communicate the means of freeing Voyager to him. (VOY: "The Fight")