A1 abstract the invention relates to a device and a method for operating an unmanned underwater vehicle wherein the underwater vehicle has determining means which determine a usability indicator a use recommendation for the use of the underwater vehicle in a future mission can be derived or is derived from this usability indicator the determination of the usability indicator takes place as a function of at least one operating parameter of the underwater vehicle a decision aid relating to the suitability of the underwater vehicle for a respective purpose of use can be made available for an underwater vehicle which can be used for different purposes by means of the invention in addition the invention relates to an underwater vehicle which has at least the determining means and or storage means for storing a usability indicator which is determined by means of the device according to the invention application_number US 201214123520 A description the fig1 shows an unmanned underwater vehicle 2 which is mounted for example on board a marine vessel and is connected by means of an electrical cable 4 to a charging control device 6 the electrical cable 4 can comprise a plurality of electrical conductors the unmanned underwater vehicle 2 comprises batteries 8 and 8 u2032 as well as further batteries which are arranged in a concealed manner and which are all configured as lithium ion rechargeable batteries which can be charged up and the charged state thereof being monitored by means of the charging control device 6 via the electrical cable 4 if the charged state falls below a value of 60 percent of the charging capacity of the batteries 8 and 8 u2032 the charging control device 6.