This category is the horizontal equivalent to the Unassisted Constant Ballast vertical type of diving, and as such it can also be considered the hardest type of horizontal immersion. The diver must reach a length without the aid of any swimming equipment, while keeping all other gear used such as masks, suits, etc.

Interesting Facts:

-Though many divers have experimented with several new styles and variations, the most effective technique for this category is still the old breast-stroke used by swimmers.
-Good horizontal unassisted divers can cover a 50 meter pool in only 6 strokes, giving them a displacement of 8.3 meters/ 27.3 feet per stroke!