Late on the morning of April 3, the expedition ship Alucia rocked violently on the South Atlantic Ocean in the middle of a squall. On the aft deck, the crew huddled together in rain slickers and gazed across the heaving seas to a yellow blur on the horizon. This was an unmanned reconnaissance submarine carrying 15,000 photographs that they were nearly desperate to see. But it had buoyed to the surface just as the squall sprang up, and with 30-knot winds and four-foot swells that splashed over the stern, it was too dangerous to retrieve the sub. So they watched and waited.