Successful diving in current means you're drift diving, (diving with the current, using it to transport yourself with minimal effort and live boating - meaning the boat follows the divers on the surface and picks them up at the end of the dive)
While I think it's a valuable asset and a life-saving choice in diving to be in good shape, I'm just pointing out that drift diving done properly is easier on the body than any other type of diving you can do. You go with the current you do not fight it. People who drift dive take on the drift diver posture which is arms crossed, barely moving the entire dive, they move in slow motion the entire dive and enjoy long bottom times due to not expending much energy.