Sidemount configuration offers a more streamlined profile for scuba diving. Kwok demonstrates in Sun Yat-Sen University's diving pool in Guangzhou.

Like most scuba training involving new equipment, you start in a swimming pool. This session took place in Guangzhou.

Sidemount training in Guangzhou. Or, just having fun... Adjusting the trim and balance is easier with sidemount, and allows you to move freely in any direction.

If you wear two cylinders, they can be smaller than what you normally use.

With sidemount, you usually gear up in the water: no need to carry the tanks on your back to the water's edge.

Kwok snapping a photo of a whale shark in Moal Boal.

Many divers choose to wear two cylinders for sidemount diving for redundant air source and more stable balance.

Smaller cylinders are easy to handle.

Since the tank valves are right in front of you, it is easy to turn the valves on and off, should you need to. You don't need to take the tanks off to do this.

Comparing different configurations for technical diving: twin set, sidemount, rebreather.

You don't necessarily need to dive pushing the tanks, but you can if you want to...

Streamlining with sidemount - less drag, easier to dive. You can hardly see the tanks when looking from the front.

Sidemount courses require some pool training and a couple of open water dives for the certification.

Sidemount is popular choice in caves in the cenotes of Mexico.

A diver in sidemount configuration seen from below. Photo taken in Moal Boal, Philippines.