It is interesting that you discuss Thunderball here, as I knew some of the Pararescuemen who made the parachute jumps for the movie. They were not paid, and the jump was actually written off as an USAF parascuba training jump. It was out of an HC-97 aircraft, which was notorious for being difficult to jump from. All the jumpers were given wet suits, scuba tanks and regulators for the jump (AMF Voit double 38s, I believe. I remember diving with one of the jumpers, who brought his tanks from that jump to dive Alexander Springs in Florida. That was in 1970. I took the enclosed photo of him in the springs at that time.
How does this come under the discussion. Well, when we jumped parascuba, we had quite a load of gear. We usually jumped with a main over our scuba tanks, a reserve parachute on our chests, and a "butt boat," or single-man life raft slung behind us under the tanks. We usually also jumped a medical kit below the reserve (but on Thunderball, they jumped "Hollywood," which is to say without the medical kit or life raft. Because of the load, we almost always wore two knives.
One was on our leg, with the knife worn on the inside during the jump. This was so that it would not tangle with lines if we inadvertently tumbled through the lines during the parachute-opening phase of the jump. Many of the aircraft were difficult to jump with full scuba gear. The HC-97 was notorious for problems as the jumper had to jump out the ramp, and fall some ten feet before hitting the airstream. Just a little out of position, and the jumper would either twist badly during the jump, or tumble through the lines. The HC-130 was almost as bad, but we jumped that from the side doors. That put us not only in the airstream, but also into the prop wash of the inside turboprop engine. If you did that jump wrong, you could completely loose control of the canopy from either twists or tangles. I watched one jumper in Japan, who was nailing the target, get to 100 feet and we were really encouraging him to hit it. He shouted down, "I can't control this thing!" and he couldn't either, as the parachute lines went from the parachute to the risers, which were neatly tucked under the twin tanks he was wearing instead of hooking directly into the shoulder harness. He was coming down attached from the back of his tanks, face-first, with absolutely no control of the parachut.
The other place for a knife was on the top of our reserve parachute. We could grab this knife easily if we couldn't get to our leg knife. But I never had to use it in almost ten years of jumping.
Take a good look at the actual jump in Thunderball, and you will see it was not a precision jump. Usually for precision, we only jumped two jumpers at a time. They could land within 50 feet (sometimes right on top too) of the target. But on Thunderball, the jump was a mass exit, and they must have spread jumpers over about a quarter mile of ocean (that's being kind). But it made for a good movie effect, and the jumpers got to keep the equipment after the jump.
You can see what we looked like in the enclose photo of a US Air Force Pararescuman on a parascuba jump in Okinawa (now Japan) in 1969. I had one instance where, if it had not been a training jump, I would have used my knife (other than the one described in my first entry). I was making my last qualifying jump, a night parascuba jump as a student into Eglin Bay, Florida. When I got an open canopy, I found that the right side of my risers were tied together with a half-hitch from one of the lines. This meant that I couldn't steer the parachute from that side, as they were sliding risers. There was a metal fork which fit into woven openings around the Capewell Release, which are to be pulled after the 'chute opens. But since I could not steer from this side, I did not pull that side's fork. I steered only from one side, and made a bad, downwind entry. When nearing the water, we released one riser group, and held it in our hand (you can see the jumper in the photo doing this--as he hits the water, he releases the riser, and the parachute collapses so he is not dragged). I did not do this correctly, and the 'chute did not deflate. I was in the water, being dragged a bit, and finally released the Capewell for the riser, but with the fork still attached, the parachute still did not deflate. I had to release the other one to get stopped, and then as I got my breath, I was drifting into the parachute lines. They wrapped around me and my tank. I was picked up by the recovery boat, and the NCOIC on board asked me very pointedly what I would do if that was a mission. I told him that I would simple cut all the lines, and free myself. He didn't believe me until I showed him my diving knife (which was actually my own, and not an issued one, which I had kept very sharp). The knife was like a razor, and would have made short work of the lines. That answer satisfied him, but I still got gigged for the jump.
John