Visible crew/equipment: During Bud and Coffey's fight in the lab, we see a lightbulb swinging from side to side between the two men. If you look closely, you can see a hand (belonging to a third person) pushing the lightbulb. The only people in the room are Bud and Coffey. (01:44:16)
Visible crew/equipment: Watch the special edition version of the movie. During the scene when the crane is falling down on top of the sub, the camera is following people around the passages. When it comes to the end of a hall, and a hatch is shut in our face, we can see the shadow of the camera equipment in the door. (00:54:13)
Visible crew/equipment: During the scene where Bud and Lindsey are arguing about who will wear the scuba equipment back to the rig from their downed mini sub, a hand with a cloth wipes water off the camera. It's during the line when the camera is facing Bud and he says "Don't argue with me goddammit, just put it on." This is visible in the 4:3 version for TV, as well as the widescreen version on DVD.
Visible crew/equipment: The ship is moving underwater and explosions are going off left and right. The main female character says she is going to check the battery room. As she goes, the camera is in front of her, and its shadow, including a microphone antenna are on her.
Answer: The technology does exist, yes. Read http://en.wikipedia.org/wiki/Fluid_breathing for details.
Tailkinker ★