The invention relates to an underwater switch unit for voltage supply of electrical devices (11), particularly in the low voltage range, having a housing (19) which is preferably designed to be water-tight, in which an electronics unit (2) is arranged, by means of which an input voltage, which can be connected via an input connection of the underwater switch unit (14), can be distributed in parallel to a plurality of output connections (16) of the underwater switch unit (14), wherein at least two of the output connections (16) can be supplied with voltage separate from each other via at least one switch element (7, 8) of the underwater switch unit (14), and wherein the uncontrolled underwater switch unit (14) comprises a data bus connection having a related data bus interface, via which an informational signal concerning the voltage connection of an output connection (16) can be detected.