Sidemount configuration has been a choice for advanced cave divers for years, but now it is popular for many types of divers.
Sidemount employs innovation and discipline to produce an arrangement of scuba unlike any the typical diver is accustomed to. When used in the overhead (wreck/cave) environment Sidemount is by far the ideal configuration.
Instead of carrying a redundant primary air source on the back, Sidemount utilizes the versatility to split the typical twin cylinders and relocate them under each arm. The low vertical profile of the diver's air supply allows the scuba cylinders to be easily manipulated, and carried in a less cumbersome manner.
No Limits: Technical Diver Training