The giant phantom jelly was filmed by the Monterey Bay Aquarium Research Institute at a depth of 3,200 feet.
The Texas millionaire shared photos and footage of his latest dive to the San Cristobal trench.
Sea stingers could be bred to turn into high protein powders or jellyfish chips, according to scientists.
"JELLYFISH JAMBOREE !!" Moody wrote in the Facebook post. "I've never seen this many at once before?!"
People do all kinds of things for views on social media, but licking a deadly Portuguese man o' war is undoubtedly a step too far.
There are around 2,000 known species of jellyfish, the most venomous being the Australian box jellyfish.
Over Easter Weekend, five people, including three children, were hospitalized for Irukanji jellyfish stings in the Whitsunday Islands.
"There are years when blooms or populations of a jellyfish are high and there are also years when they are few or even almost absent," said Sheldon Rey Boco, who filmed the event.
Upside-down jellyfish are found in warm coastal waters—such as mangroves, bays and lagoons—around the world.
"If we can find a way to direct these jellyfish and also equip them with sensors...we could create a truly global ocean network," said lead Caltech researcher John Dabiri.
The venom of some box jellyfish species is considered to be among the most powerful in the world.
While jellyfish are fairly common in the area, such large congregations are quite unusual at this time of year.
Some species of jellyfish are able to grow back tissue that has been lost.
Jellyfish larvae can get trapped in bathing suits and sting the skin.
The creatures pack a powerful sting that can be excruciatingly painful to humans, and in very rare cases, may cause death.
Study says the finding of an "intermittent anus" may shed light on the evolution of our own.
Sea lice are not actually lice; they are the larvae of jellyfish and sea anemones.
Summer winds left the Catalan shoreline covered in thousands of blue jellyfish-like animals.