The final stages of recovering the deep-diving submersible Alvin to its support ship, the R/V Atlantis, involves attaching a tow line to the sub. Alvin technician Anton Zafereo tosses the line to a swimmer during a 2009 recovery operation near Costa Rica. The swimmer then grabs the hook, which has a float attached to it, and brings it out to the sub. Once Alvin is beneath the A-frame, the main lift line is attached and the sub is brought on board.
(Photo by Lance Wills, Woods Hole Oceanographic Institution)