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Excerpt:

Each drone is a 23-foot neon-orange sailboat that catches wind with a solid wing more durable than a cloth sail. As the name implies, they’re seaworthy, autonomous robots, though a human pilot can take control remotely. In mid-March, two saildrones packed with sensors, cameras, and scientific instruments launched from a dock in the Bay Area city of Alameda, gliding past Alcatraz and beneath the Golden Gate Bridge to begin a three-week, 1,200-mile journey to the Shark Cafe.

By early April, the saildrones arrived and began picking up signals from a group of 37 sharks that researchers had tagged with acoustic transmitters. The drones pinpointed the sharks’ locations, then sailed back and forth, using sonar to see what they were up to. Via satellite, the drones relayed images and other data to Barbara Block, a Stanford marine biologist who started planning a research voyage to the Cafe three years ago. Block has studied these sharks for much of her career, but this was her first detailed look at their vast deepwater playground.