Hokusai is a rayed impact crater on Mercury, which was discovered in 1991 by ground-based radar observations conducted at Goldstone Observatory.

Its appearance was so dissimilar to other impact craters that it was once thought to be a shield volcano.

However, improved radar images by the Arecibo Observatory obtained later in 2000–2005 clearly showed that feature B is an impact crater with an extensive ray system.

The bright appearance of rays in the radio images indicates that the crater is geologically young; fresh impact ejecta has a rough surface, which leads to strong scattering of radio waves.

[4] The crater has a diameter of about 100 km; the rays extend for thousands kilometers, covering much of the northern hemisphere.