From a modest amount of research I'd say this is a Bulova Deep Sea Chronograph circa 1969. Most other examples I've seen date from slightly later and have an additional '666 feet' marked on the dial. The bezel is fixed and incorrect. I'd love to find an original replacement for it and would consider one in any condition to help complete the watch.
Hello ollie23, welcome to myBulova. I don't think there's any doubt that this is a Deep Sea. It's a shame that the original bezel had to be replaced. Finding a replacement will be a challenge I'm sure. Other that the bezel, the watch appears to be in very good condition, thanks for sharing it.
1969 Bulova Deep Sea Chronograph
Agree with Deep Sea Chronograph
+1
Deep Sea Chrono, hopefully you can source an original bezel.
+1