Previously called Powersnorkel, almost the same as Snuba, SASUBA - Surface Air Supply Underwater Breathing Apparatus.
An easier description is that Sasuba is between snorkeling at the surface and diving deeper with tanks. Instead of wearing all of the bulky scuba gear, you just click Sasuba on and after a short instruction away you go.
The air line from the floating scuba tank supplies air to the diver. It is much easier to use than a snorkel . Fully supervised at all times.