The Mariana hadal snailfish, Pseudoliparis swirei, a recently described snailfish species living below a depth of 6,000m in the Mariana Trench. We provide chromosome-level genomes of hadal snailfish and Tanaka snailfish, as well as more resequencing and transcriptome data to analyze and determine the adaptive changes of hadal snailfish to the high-hydrostatic pressure, dark environment of the hadal zone.