Buoyancy control, trim, and finning.
I have on multiple occasions seen divers with technical certifications bouncing off the silty bottom of Dutch Springs or the Atlantic Ocean, or kneeling on a wreck in the St Lawrence, or swimming along, scissor kicking a gigantic trail of silt behind them. I have seen them kicking straight up from the bottom, creating a huge cloud of silt, just to ascend.
I have on multiple occasions seen divers with technical certifications bouncing off the silty bottom of Dutch Springs or the Atlantic Ocean, or kneeling on a wreck in the St Lawrence, or swimming along, scissor kicking a gigantic trail of silt behind them. I have seen them kicking straight up from the bottom, creating a huge cloud of silt, just to ascend.