Phoenix Logs/Multiplayer Maps/Rift
From Halopedia, the Halo wiki
The battles fought at this Forerunner array will echo through history.
A monolithic Forerunner structure dominates this environment, sitting atop a churning whirlpool that harnesses the power of subterranean rivers and waterfalls that flow into the ocean. Though one side remains unsullied by the war, the other is pitted with large breaches in the surface as the Banished tunnel downwards to plunder the Ark's valuable resources.