The EX1605L1 leg of NOAA Ship Okeanos Explorer‘s trip to the Marianas was captivating, to say the least! From new species of jellyfish, to hydrothermal vent chimneys, this exploration leg was jam-packed with discoveries.
Okeanos started this cruise leg near Guam, then moved towards the Marianas Trench Marine National Monument (MTMNM) and the Commonwealth of the Northern Mariana Islands (CNMI). The Marianas Trench is known as the deepest part of the ocean, at almost 11,000 meters deep! The intention behind this cruise leg was to gather baseline knowledge of the biodiversity and geology of the area. The NOAA team onboard used their remotely operated vehicle (ROV) Deep Discoverer, “D2” to explore the area.
As always, the Inner Space Center at URI published those streams in real-time to YouTube and scientists worldwide. Some dives attracted as many as 2,500 simultaneous viewers.
The biology encountered in the Marianas was phenomenal! The cruise leg started off with a six-gill shark sighting at Santa Rosa Reef.
We discovered a wide variety of creatures inhabiting the area:
One of the most enthralling discoveries was a new species of jellyfish! This hydromedusa was found at Enigma Seamount at roughly 3,700 meters:
The Okeanos Explorer also made some great geological discoveries. They explored a newly-discovered hydrothermal vent site boasting one of the highest temperatures recorded in the Marianas region: 339 degrees Celsius. (Most of the deep sea is a chilly 2 degrees Celsius.) The 30-meter chimney base was releasing black “smoke” made up of iron and anhydrite precipitate.

There were also young lava flows that had created glassy pillow mounds. The area was so new that no animals had yet colonized the area.
That’s a wrap for Leg 1! Come back for more deepwater exploration on June 17th!
For more details about individual dives visit the NOAA Okeanos Explorer website.
Videos and images courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Marianas.