Boreas is a wristwatch by Martin Braun.

Astronomical watch with automatic winding, which can indicate the sunrise and sunset times as well as the equation of time. For a correct display each watch is individually adjusted to the place specified by the buyer. This watch, as usual with Martin Braun, can be obtained in several versions that differ primarily through the dial and the bezel. On the left side there is the dial indicator for the sunrise periods, on the right for the sunset times. Since this is an astronomical display, daylight saving time is not considered.

Overall, the watch is very similar to the EOS, which is also reflected by its name Boreas in Greek mythology is the child of Eos, the goddess of the dawn. The main difference from the EOS is the additional indicator of the equation of time, an astronomical complication, which indicates the difference from the mean local time to true local time.