Complex sentence: The Watchers are associated with a submerged reef system independent of that underlying the Waldegrave and Little Waldegrave Islands and where the water depths drop to within about immediately south and west of the western rock about to its north east.
Split into simpler sentences: The Watchers are associated with a submerged reef system independent of that underlying the Waldegrave and Little Waldegrave Islands. Waters adjoining the Watchers drop to depths of within about immediately south and west of the western rock and about to its north east.