This beautiful, big medusa belongs to the genus Cyanea, which is a group of scyphozoan jellyfishes well known for their tendency to "bloom" and occur in large numbers in surface waters. They can also be a major food item for leatherback turtles. For many years it was thought that there were only a few, mostly cosmopolitan species, but we now know that many morphotypes are actually valid species in their own right.
This jelly was seen during a Windows to the Deep 2018 dive to explore along the north wall of Keller Canyon, about 26 miles from Cape Hatteras, North Carolina.
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Video courtesy of NOAA Ocean Exploration, Windows to the Deep 2018.