Basic Panel: Temp +40 (add yellow), Tint +35 (add magenta). This is the crucial step to remove the strong blue/green cast.
Basic Panel: Highlights -40, Shadows +60, Exposure +0.50.
Detail Panel: Noise Reduction (Color) +40, Noise Reduction (Luminance) +25 (underwater shots are often noisy and lack color data).
HSL Panel: Blue Saturation -30, Aqua Saturation -30 (to neutralize the water).
Masking (Diver): Select Subject. Inside mask: Shadows +20, Clarity +10, Saturation +5.
Masking (Vignette): Add an inverted Radial Gradient around the diver. Inside mask: Exposure -0.40, Dehaze +10 (to darken the water).