Johns Hopkins' drone flies straight from an underwater station

In addition, the engineers sealed its most sensitive components inside a dry pressure compartment. They also painted its exposed parts with commercially available coatings that can protect them against the corrosive properties of saltwater. Both measures seem to have worked well during their experiments: the drone the researchers kept in sea water for two months showed no signs of damage. CRACUNS doesn't have any metal parts that can rust and malfunction in the water -- best of all, it's lightweight and doesn't cost much. Those factors make it a good candidate for big research or military operations.