Russia has released footage of its 'scuba tank crews' going underwater during a training exercise.
The T-72 main battle tank can be fitted with a snorkel for deep fording, and takes about 20 minutes to prepare for amphibious use.
In the video, the B3 variant, which can operate up to five metres underwater, is completely submerged.
Tank drivers then have to use specially-made instruments to steer the machine in zero-visibility conditions.
Also part of the training was teaching troops what to do in a worst-case scenario - if the tank gets stuck...