AbstractA scheme is suggested providing an overall account of vertical wavenumber spectra of velocity and temperature in the ocean. The account ranges from vertical scales of hundreds of metres to scales of millimetres. Larger scales are dominated by quasi‐random shear refraction of internal waves. Smaller scales are dominated by parallel cascades of kinetic and potential energy. In contrast to previous ideas, the present scheme suggests that vertical mass flux p'w’ plays no dynamically significant role at any length scale. Efficiency of vertical mixing must be very small. Small‐scale spectra are assumed to be in equilibrium with respect to variance production, transfer and dissipation; no significant “fossilization” is expected.