Butterdezillion is continuing on her theme of a Loretta Fuddy murder or abduction with some still shots from ABC footage of the passengers in the water taken by Mr. Puentes. The stills that come from the sequence beginning around 3:30 in the Nightline video for just a moment show something that might be imagined to be a scuba diver wearing a raincoat and a big floppy hat, but in the whole sequence viewed in motion looks like debris. Certainly if it had been a real diver, there would have been a reaction from the people in the water, which there was not.
The way I look at these things is to download the video and then single-step with QuickTime (the arrow keys move by one frame).
Also in the video I found a young man wearing glasses and a pointed wizards hat riding a motorcycle.