The expression for the bottom convection intensity is derived from the equality of the advective vertical flux of H₂S within 1000–2000 m to the diffusion turbulent flow close to the H₂S zone upper boundary. The upwelling rate, which is expressed via the H₂S concentration in deep waters and the gradient of the H₂S concentration near the upper boundary, is 10^–4 cm/s. It is shown that the H₂S diffusion flux in deep waters is an order less than the advective one. The conclusion that below 1000 m the age of H₂S does not exceed 30 years and H₂S reaches the upper boundary in approximately 150 years is derived.