As we headed out to the dive site, one of the crew mentioned something about feeding the sharks. We thought he was joking. We had not signed up for a shark dive. .......Unbeknownst to us, while we were struggling to get back to the mooring line, the crew was chumming off the stern of the boat with fish parts. I was still at 50 feet on my way back to the mooring line, and upon looking up, saw a feeding frenzy of grey reef sharks under the boat and by the ladder. Diver number 1 left the mooring line for the ladder, but missed the ladder and the strong current carried her away from the boat. There was not a tag line off the back of the boat. Exhausted, Diver 1 kicked on her back and flailed with her arms, further exciting the sharks below her. One of the crew jumped into the water to pull her to the boat. We witnessed the sharks arching their backs and shooting toward the surface directly under dive 1. Diver 8 was still on the mooring line witnessing the scene. After getting onto the boat, diver 8 was so upset about the shark incident and exhausted by having to tow her buddy against the current at depth, that she sat out the second dive.