The Mysterious Rings is a discovery which hints to the existence of the Will o' Wisp discovery. This Discovery lies in extremely close proximity to the Will o' Wisp discovery, Both of which are located in the North Ocean, which can be accessed once the Iron Net has been removed by the Valuans. It is located on an island which is invisible until discovered, just off the coast of one of the southern islands in the western area of the North Ocean.
It can be speculated, given the look of the discovery, that this is an incomplete version of a Black Moon Stone crest. The rings have seven circles around the center of the rings, instead of one to six like the others and the lines make up part of the design. However, nothing confirms this and could be merely coincidence.
"Huge geometric shapes that mysteriously appear on the ground overnight. Reports have been very frequent lately. Old records speak of a similar phenomenon, and mention 2 or 3 glowing balls of light that appear the night before the shapes are found."
The actual discovery is not just the rings, but an entire island, with the rings etched on top of it in a similar style to the Great Bird.
This discovery can be irritating to find, as it is found in otherwise empty sky in the North Ocean. This discovery is in very close proximity to the Will o' Wisps, which is on the next island north of the of the Roc's Nest, and is located about 8-12 ships lengths off the southwest coast of this island. The discovery is in the area of North Ocean dominated by the presence of the wall of thick dark clouds which cannot be passed through at any point in the game. Sometimes the Black Spell Pirate vessel which wanders around the southern area of North Ocean can move to be barely in visible range of this discovery, but this is unhelpful in finding the island.
The most surefire way to find this discovery is to travel from the Roc's Nest discovery in a direct line to the Will o' Wisps discovery. When the ship is within examining distance of the Will 'o Wisp's, pivot on the spot approximately 90-degrees to the east (a sharp, street-block style right turn), and travel about 8-12 ships lengths in a straight line off the coast. The compass should begin to spin after a medium distance, if it doesn't then the ship is probably very close to it. If a short sweep does not produce the discovery, loop back around to the Will o' Wisps and try again, but heading out from the island at slightly different angle, in the same general (east to south-east) direction. The island is fairly large, so passing anywhere near it is usually enough to make the compass spin, so extreme precision will not be needed.