Sargasso (wildspace)

The sargassos were twelve enormous dead-magic zones that closely orbited the sun of Realmspace and presented a major hazard for spelljammers traveling in that area.

Geography
Each sargasso was a globe about 100,000-mile (160,000 km) in diameter. They orbited the sun from a distance of 40 million miles (64 million km) and were all equidistant to each other. From that orbit, they could pass as close as two spelljamming hours away from Anadia, which orbited at a distance of 50 million miles (80 million km) from the sun.

A spelljammer that entered a sargasso powered down in bursts until the spelljamming helm and any other magic items onboard stopped working within a few seconds, giving very little time for the navigator or the crew to react. For the helmsman, the sickening feeling of an approaching sargasso was similar to that of falling off a cliff. If the helmsman were unsuccessful in maneuvering the ship away, it slowly drifted into the sargasso carried by its own inertia, incapable of escaping until it reached the other side, which could take months.