Vertical currents are especially challenging for divers.
The safest way to handle vertical currents is to avoid them. Vertical currents typically occur near the face of a a wall or open ocean pinnacle. They are either down-welling or up-welling. Down-welling currents are currents that push you deeper/down where as up-welling currents force you up towards the surface.
In either case, the trick is to swim away from the face of the wall or open ocean pinnacle at a 45 degree angle in the opposite direction of the vertical current while adjusting the air in your BC to either increase or decrease your buoyancy as needed.
Watch the following video demonstration of how to manage vertical currents below.
Image Source: YouTube Clip
See next page below to find out how a group of divers cope with being caught in a down-current at Maldives