Deepest lock on this part of the river

We're on our way to Viviers today, but at 8.30 am we had to negotiate this lock.  The first extra gives some indication of how deep the lock was so it took some time to fill.  
Viviers itself is very small with a population of only around 3,600 people, but it is probably the smallest city in France - made so by being the see of the Bishop of Ardeche and has a cathedral. The buildings are very old and streets very narrow, hardly able to accommodate the cars that drive around.  There are also lots of restrictions on how much renovation can be done to its buildings (extra 2)  .  Because the city is very small, the tour guide was very slow at walking and talking, and I have to confess we made our own way back to the boat after an hour.