Hydrostatic pressure plays a critical role in shaping the distribution and activity of microorganisms in deep-sea environments by influencing microbial physiology, structuring communities, and selecting for pressure-adapted taxa. Marine filamentous fungi and yeasts have been detected across diverse marine habitats, from coastal waters to the deep subsurface. While deep-sea fungi, particularly those inhabiting bathypelagic and deeper realms, remain poorly understood, recent studies have begun to uncover their diversity and suggest their non-trivial ecological functions in these extreme environments. This review synthesizes current knowledge on the biodiversity of deep-sea and deep subsurface fungal communities, with a particular focus on yeasts, and provides insights into yeast strategies for coping with challenging hydrostatic pressures.