It's a lot better than even money that the visibility in salt water off of Aruba is even greater than the "fresh" water in the Hudson and Harlem and East Rivers in New York. Baden was a coroner in New York City who eventually became the Chief Medical Examiner for New York City and later the New York State Police. Those are the offices that examine the bodies that are found in those bodies of water, and there have been more than a few over the years. The East River in particular is a well known dumping ground for Mafia hits in New York. I am quite certain that, over the course of his career, Baden examined dozens if not more bodies that had been dumped into those particular rivers. This would include examining photos of the bodies in-situ before they are brought up.

Now how many decomposed corpses under water have you seen? Because there is no doubt that Baden has seen quite a few of them. And probably some of them in salt water as well, as New York Harbor is salt water.