 Surface supplied divers may be supplied with a gas mixture suitable for accelerated decompression by connecting a supply to the surface gas panel and connecting it through the valve system to the divers.This allows accelerated decompression, usually on oxygen, which can be used to a maximum depth of 20 ft (6 m) in water for scuba and 30 ft (9 m) on surface supply.Surface supplied heliox bounce divers will be provided with mixtures suitable for their current depth, and the mixture may be changed several times during descent and ascent from great depths.