The vintage Scubapro 500 was engineered as a "set it and forget it" survival tool with a 500-meter (1,640-foot) depth rating, where the cost of failure was human life. Lacking modern ISO standards to define minimum strength requirements, Scubapro (a dive supply company, not a watchmaker) chose to err heavily on the side of caution. The result was a massively over-engineered instrument built with a "safety first" mindset that prioritized absolute survival over comfort or elegance.
Croton Chronomaster Aviator Sea Diver (which is in the running for best watch name, ever).
This is a 2nd generation model with a Valjoux 92 (105/9855) and made between 1962 - 1966, the Tritium dial tells us it wasn't made right at the start of production. Brilliant broad arrow hands, about 98 functions packed into a singe chrono and a the minute counter is a jump counter to help regatta timing. Came to me recently from a PEI estate/downsizing auction claiming a recent service. All original except for the sub-dial seconds hand which is an incorrect replacement. If you have a copy of the "Chonomaster Only" book, let me know.