An approximation to the internal gravity wave spectrum (for waves with large horizontal extent compared with the vertical extent) which is observed to have the same structure throughout the deep ocean. The energy density spectrum is proportional to Ef/omega (omega^2-f^2)^(-1/2) ~= Ef/omega^2 (for omega>>f) for waves of frequency omega in which f is the Coriolis parameter and E is a nondimensional parameter empirically determined to be E ~= 6*10^(-5). For a wide range observations E has been found to vary by no more than a factor 2.