Is it set in modern times ? Lots of things have changed since my days. There was a diver's manual although I never saw one. That might help as I note your "and I'm keen to get my facts right as far as possible".
Reading your initial post again looks like the divers are more for under water search than recovery of the body?
Yes, set in present day. And yes, divers were for a subsequent search - I didn't have specialists recovering the body, but it seems I should change that...?