From Halopedia, the Halo wiki
The Aleutian Rim is a rim of the Cortez Ocean on Beta Gabriel, a human Inner Colony planet. The Office of Naval Intelligence's Fathom Station was constructed at the Aleutian Rim to allow ONI to search the nearby remains of Covenant carrier Splendid Intention for weapon plans following the Human-Covenant War. However, in 2556, Splendid Intention suddenly shifted from its resting place along the rim and slid down a trench, sending debris and water into Fathom Station's northern terminal, ultimately destroying the station and eventually leading to the deaths of all the station's personnel.
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