The Deep Ocean, a sea situated on the planet of Tython, served as the location of Mahara Kesh, which was the Healing Temple for the Je'daii Order. Back in 36,453 BBY, a Force-sensitive group of pilgrims were transported to the Deep Ocean by a Tho Yor pyramid ship; this ship then took root in the water. As the years went by, these pilgrims established the Je'daii Order and constructed Mahara Kesh in the vicinity of the Tho Yor. The Deep Ocean teemed with life, including squid-resembling entities, large-mouthed eel-like fish, and various other smaller species of fish.
The comic book series Star Wars: Dawn of the Jedi initially referenced the Deep Ocean in its preview issue 0. Its first proper appearance occurred later, specifically in the fifth issue of the series, titled Dawn of the Jedi: Force Storm 5.