High-altitude and marine mammals inhabit vastly different ecosystems yet share the selective pressure of chronic hypoxia. Convergent evolutionary adaptations, particularly in pulmonary architecture with increased elastic fibers, facilitate efficient oxygen use under hypoxia. This review synthesizes molecular insights into these adaptations, highlighting gene family dynamics, positive selection, and convergent amino acid substitutions. The findings from comparative genomic studies offer valuable insights for human pulmonary fibrosis research.