Transportation on the surface can be easier either with backmount or with sidemount, depending on requirements. Carrying weight on the back is less stressful on the spine than carrying it to one side when out of the water, so for carrying a single cylinder, a backpack-style backmount BCD can be more comfortable. A heavy twinset can be unwieldy and heavy on the back though. In the case of sidemount, the two cylinders can be carried separately, distributing load and making transport on rough ground easier.