I'm not sure we're there, yet, today. Yes, I've seen the video where Casey Neistat hangs off a drone in ski gear. But to attempt a rescue, the drone is pullin

I'm not sure we're there, yet, today. Yes, I've seen the video where Casey Neistat hangs off a drone in ski gear. But to attempt a rescue, the drone is pulling against somebody who isn't trained (more movement means harder to stabilize). You're also fighting against the ocean, so you're going to need extra power to pull the person against the waves, at least until you get them plucked out. As mentioned elsewhere in this thread, the drone will need to operate quite a bit higher up to stay safely clear of water and heavy spray, so the person would be at the end of a much longer rope, and a longer rope means the system is a longer "pendulum", which again means it'll take more energy to stabilize it. An ocean rescue is going to happen on a warm day, whereas the Casey Neistat video was done in cold, dense air where drones are more efficient. I would not be surprised if it takes an order of magnitude more energy, at the drone, to pull a person out of the ocean that it takes to lift a calm person on dry land. That's a big hill to climb.