The absorption coefficient of water for light of wavelength 450 nm is roughly 450 0.0001

The absorption coefficient of water for light of wavelength 450 nm is roughly κ₄₅₀ ≅ 0.0001 cm⁻¹ while for light of wavelength 750 nm it is roughly κ₇₅₀ ≅ 0.03 cm⁻¹. Estimate the depth by which 90% of light has been absorbed by the ocean in each of these wavelength ranges. Explain the color seen underwater at typical depths encountered by divers.