The single lock on the left has its door in the "down" position and a boat can just barely be seen above the door inside the lock.  That little tinge of blue is a boat transiting downstream.  Once inside the lock, the entry door is closed and the lock is drained, lowering the boat.  Then the downstream door opens to let that boat out, and a boat transiting upstream enters.

'RP Wien' gets ready to take its place in the lock.  The downstream door closes.  The lock fills, lifting the boat up to the next level.

The Var, its turn having finally arrived, slides into the lock.  Marcia Emmett demonstrates how much (how little) overhead clearance the boat has.  For this passage, the wheelhouse has been telescoped down into the Var to reduce its height.

Looking aft, we can see the wheelhouse partially depressed and the downstream lock door still in the raised position.

Flooding the lock.

Almost there.  In a moment, these upstream doors will swing open to let us out of the lock, and that boat visible straight ahead will take our place as soon as we have cleared the way.