From Halopedia, the Halo wiki
The Cortez Ocean is an ocean on Beta Gabriel, a watery planet and a human Inner Colony. The ocean is home to the qothal and the paelosur, which are often found in the depths of the ocean. The Cortez Ocean was the location of the Aleutian Rim.
During the invasion of the Epsilon Eridani system in the summer of 2552, an engagement over Beta Gabriel led to Covenant carrier Splendid Intention and UNSC Of Uncommon Courage crashing in the southern waters of the Cortez Ocean. Following the Human-Covenant War, the UNSC Navy's Office of Naval Intelligence established Fathom Station in 2554 near the crash-site of Splendid Intention in Cortez Ocean, nestled along the Aleutian Rim. Fathom Station was utilized by ONI to search for Covenant weapon plans aboard Splendid Intention.
However, in 2556, the carrier suddenly shifted from its resting place and slid down a trench, sending debris and water into Fathom Station's northern terminal, ultimately destroying the station and leading to the deaths of 41 researchers aboard the station as well as 23 explorers trapped on Splendid Intention.
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