Superhydrophobic surfaces with quasi-aligned W₁₈O₄₉ nanowire (NW) arrays were fabricated using a simple thermal evaporation and surface chemistry modification method. The fabricated superhydrophobic W₁₈O₄₉ NW surface has shown reliable stability in submerged underwater conditions, exhibiting silvery surfaces caused by total reflection between the water layer and air pockets. The stability of superhydrophobicity in underwater conditions decreased exponentially as the hydrostatic pressure applied to the substrates increased. In addition, variations in stability were investigated according to changes in the surface energy of W₁₈O₄₉ NW arrays. As surface energy decreased, the underwater stability of the superhydrophobic surface increased sharply. Based on these results, the models explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. This study on fabrication and modeling of underwater superhydrophobic stability will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications.