A Thomas Mercer Chronometer from 1878 is the oldest one that actually runs. Just a collectors piece I wanted for a while. I have a couple of verge-fusees in various states of disrepair which are surely older, but dating them accurately is a hassle, and they don't run anyway.
Oldest watches I actually use regularily are 1950's Longines 23zs, Omega 266 and a Cyma Watersport.
Hard to see things from this photo alone, but here's what I think I see: Dive watch, -or at least dive style-, black dial, huge triangular lumed indices, also I think I see a big lumed hour hand. Unfortunately there is a huge number of such watches from many makers, they were very popular at the time. Some were very cheap with plated cases and pin-lever movements, some were proper, steel dive watches. Here's one example, from the more "affordable" side :
https://preview.redd.it/bh19mia7hi0c1.jpeg?width=1080&format=pjpg&auto=webp&s=690a0fe7a5149d3254e7843d444547f2dc133b60