Deep in the ocean, a mission is underway to explore the "unknown and poorly known areas" around the Mariana Trench.

"Despite decades of previous work in the region," the National Oceanic and Atmospheric Administration says, "much of the [trench] and surrounding areas remain unexplored."

Between April 20 and July 10, the government agency and its partners are collecting and sharing data on the creatures and habitats they find in the Mariana Trench, which stretches 1,500 miles in the Pacific Ocean near Guam.

You can follow NOAA's live video streams from the Okeanos Explorer, including images from the ocean floor. (Sometimes the streams show maps and computers rather than sea creatures, but you can see video highlights here, too.)

It's all pretty mind-blowing when you think about it, but here are a couple highlights:

A mesmerizing jellyfish found around 3,700 meters (2.3 miles) down.

"At the beginning of the video, you'll see that the long tentacles are even and extended outward and the bell is motionless," NOAA notes. "This suggests an ambush predation mode. Within the bell, the radial canals in red are connecting points for what looks like the gonads in bright yellow."

Watch this purple sea cucumber undulate through the water.

Also, "pillow lava."

"These pillow basalts ... form when basaltic lava erupts underwater," NOAA explains. "Cold seawater chills the erupting lava, creating a rounded tube of basalt crust that looks like a pillow. As the newly erupting lava pushes through the chilled basalt crust, it can form scratches on the pillow surface, called striations."

Two years ago, the "ghost fish" of the Mariana Trench surfaced in the news. The "deepest living fish ever recorded" was among the discoveries from researchers who were stunned by the amount of life they found, as NPR's Christopher Joyce reported. That's despite the trench being — as Chris put it — "a place of perpetual darkness and freezing cold."

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