The Scorkl is basically a little SCUBA tank with a breathing mouthpiece. Its compactness lets you grab it in your hand on land, and between the teeth in the water, for enhanced transportability when you are going to the ocean, and more flexibility as you dive in. The Scorkl tanks retains sufficient oxygen for about 10 minutes of underwater excursion.
Of equal interest, when you have drawn the Scorkl dry you can replenish it with an easy hand pump and be able to go again in seconds. (Making use of an added adapter, you may also refill the Scorkl in just a few seconds with a regular SCUBA tank.)
Undoubtedly the Scorkl air capacity restricts your diving depths, however, it still provides you with a far greater vertical reach than snorkeling, and is a lot less of an inconvenience to carry and use compared to SCUBA gear.