I am watching a rerun of the Expedition Unknown Episode titled "Captain Morgan's Lost Gold" - very interesting and I will not give up an spoilers in my comments here.
Basically, until 1999 the mouth of the Charges River was part of a large U.S. military installation known as Fort Sherman. That installation was a major jungle warfare training center for the U.S. military and as a result, thousands of U.S. military personnel and their families have been to the mouth of the Chagres over the decades. It was well known that numerous shipwrecks were located along the reef. As a young U.S. military officer stationed in Panama in the early 1990s and then expat several years later, I personally snorkeled along that reef and spotted/touched cannon and cannonballs along the seabed. Another point - there are lots of sharks in that bay!
Watching this episode, one would think that the TV crew was blazing new territory by diving in the Chagres area just under Fort Lorenzo. You would think that there have been no explorations in that area for the past few hundred years. That is certainly not the case as it is an area well traveled by Panamanians and Gringos alike over the decades. All the jungle warfare instructors I have known were well aware of the wrecks in the bay. What prevented exploration is that the location was located on a U.S. military installation and the thousands of folks who have been in that bay were too busy undergoing military training. The casual viewer of this episode would never know that.