The Stone Reefs are natural environmental barrier encountered in the world of Arcadia, and function very similarly to sky rifts in that the player cannot pass through them until certain conditions are met. A Stone Reef is best described as a massive wall of floating gravel, stone, and boulders represented as ranging in size from sand to small islands. Unlike sky rifts, Stone Reefs do not extend into the lower elevations of the sky, but it remains that they are on the order of thousands of feet tall and, in some cases, thousands of miles long (or the Arcadian equivalent thereof) generally spanning regions the size of continents or larger. The nature of Stone Reefs makes them major geographical barriers or junctions for most regions, but in some cases leads to isolated pockets of the world that are utterly cut off from the sky-fairing society. Passing through a stone reef, for those vessels capable of doing so, causes the vessel to lose half to a third of it's speed in the process. Vessels that cannot penetrate the reef will halt and eventually be pushed back out. There is mention at one point of ill-equipped vessels becoming entrapped in stone reefs and destroyed, crushed, or otherwise entrapped. Eventually players are able to simply fly over (or under) stone reefs, rendering them irrelevant to gameplay from that point on.
There are two classes of Stone Reef encountered during the story arc of the game, and although the exact difference between them is never explained, they are clearly composed of different material. The first Stone Reef encountered is composed of brown, banded, but otherwise unremarkable rock - this reef can eventually be penetrated using the Little Jack's harpoon cannon as a ramming spear. The second, much larger reef encountered later in the game is composed of very light colored stone, grey to white in color. This light colored reef cannot be penetrated by the Little Jack, presumably because the stone is much denser packed or harder to break. In fact even the high powered, heavily armored ships of the Valuan armada could not pass through the grey reef on a whim, instead at one point choosing a mass bombardment of a section of the reef to punch a gaping hole in it that they could safely fly through. The Delphinus itself - arguably the most advanced ship in Arcadia - required the outer hull be specially reinforced before it could push through that reef without any assistance.
The brown Stone Reef separates Sailor's Island and Valua from Maramba and most of the Nasr continent, it also extends into The Vortex region, the heart of Blue Rogue's territory. The Grey Stone Reef separates Yufatoma and Ixa'Taka, and actually circles the entire planet of Arcadia effectively separating the eastern and western societies, along with the dark rift.
Requirements to penetrate:Edit
- The Brown Stone Reefs cannot be passed until the Little Jack acquires the Harpoon Cannon in Valua. the Delphinus, also cannot pass Brown Stone Reefs immediately after being "liberated" from Valua, until after it is upgraded and optimized by Brabham before he joins the crew on crescent isle. Afterwards the Delphinus can penetrate brown, but not grey, stone reefs.
- The Grey Stone Reefs cannot be passed until the Delphinus's outer hull is reinforced to the level where it can ram through solid ice, thus gaining the ability to access the Ruins of Ice.