An underwater recreation system for diving instruction and method of its use. The method includes providing a series of learning steps with diving techniques and instructions to practice at incrementally deeper depths and providing a surface floating depth limitation device that restricts the learning user to the particular maximum depth of their learning step. The apparatus for carrying out the method of diving instruction includes a surface floating depth limitation device with the means to connect to the breathing hose of a surface supplied air supply.

The buoyancy control device for scuba diving comprises an air bladder, a harness comprising at least two shoulder straps and an abdominal strap made up of two abdominal half-straps, a backrest provided with first slots engaged by the abdominal half-straps, second slots engaged by at least one retaining strap for retaining at least one air cylinder, one or more third slots engaged by the two shoulder straps, and one or more fourth slots engaged by corresponding straps for connecting the backrest to the air bladder.

The fastening device for the air cylinder includes a belt having a first end portion and a second end portion, a coupling ring attached to the first end portion of the belt, and a buckle to which the second end portion of the belt is attached. The buckle includes locking grooves in which locking portions of the coupling ring are releasably locked. The locking grooves include openings that gradually widen toward a rear face side. The front face of the buckle includes bent portions that are brought into contact with an outer circumferential face of the air cylinder when coupling between the belt and the coupling ring is released.

A diving backplate includes a device body, a first frame, a second frame and multiple counterweights. The device body includes an inward face and an outward face opposite to the inward face. The first frame is connected to the outward face. The second frame is connected to the inward face and includes multiple first assembly holes. The multiple counterweights are detachable mounted to the second frame. Each counterweight includes multiple second assembly holes each respectively aligned with a respective one of the multiple first assembly holes. A fastener is provided for mounting with each aligned first assembly hole and second assembly hole.

A device to facilitate weight operation in a Buoyancy Control Device (BCD) is described. The device may include a tubular body made from waterproof fabrics. The tubular body may have an exterior, a top opening, and a bottom opening. The device may include a semi-rigid tab and a pair of fastening assemblies attached to the exterior of the tubular body. The top opening may have boning that supports the top opening in an open state. The top end of the semi-rigid tab is fixed to the exterior and is close to the top opening of the tubular body, the bottom end of the semi-rigid tab is in contact with the exterior as a result of a rigidity of the semi-rigid tab. The pair of fastening assemblies are positioned on opposite sides of the semi-rigid tab.