The max descent rate for the BSAC 88 Tables is 30m/min. Going quicker means the bottom time calculations are no longer valid. That said 30n/min is pretty fast.When I get in the water, I tend to dump all my wing gas and exhale and descend pretty fast. When I get to depth I add gas to the wing and level off. We always worry about rate of ascent for obvious reasons but is there an unsafe descent rate? The only thing I can think of is maybe higher chance of narcosis?