Taphephilia
From wipipedia.org

Taphephilia is a fetish or paraphilia in which an individual becomes sexually aroused by the fantasy or act of being buried alive.
Usually, such people are considered submissive because being enclosed without being able to escape induces a feeling of helplessness. Being enclosed also changes a person's breathing, which can give the feeling of being high. People act out this paraphilia by being put into latex or PVC sleepsacks, gas masks and other fetish wear.