While there are references to both a Deep Ocean Outer-ring and Deep Ocean Center in-game in various scans of creatures, there is no apparent difference between these zones in the game other than the depth of the seabed. The two sub-biomes even share the exact same creature spawn list. There are several references to ocean shallows in-game, which would best equate to its outer-ring. Because of this, unlike the other biomes, it makes more sense to equate the majority of the Deep Ocean to its center zone with its outer-ring considered the Shallows.
While on a raft, the deep ocean is the safest biome to traverse.