Surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) for an underwater vehicle (10; 100a, 100b) movable in the three-dimensional underwater space in the x-, y- and z-direction, comprising: control means for moving the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) in the x- and y-direction on the water surface; a receiver for receiving position information for the position of the underwater vehicle (10; 100a, 100b); a control computer for controlling the control means , wherein the control computer is configured to control the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) such that the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) follows the x- and y-direction of the underwater vehicle (10; 100a, 100b) in the x-and y-direction. wherein the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) comprises a transmitting unit configured to emit a first signal such that a runtime of the first signal can be determined by the underwater vehicle (10; 100a, 100b); wherein controlling is carried out such that the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) is positioned substantially perpendicularly above the underwater vehicle (10; 100a, 100b) to emit the first signal substantially perpendicularly in the direction of the position of the underwater vehicle (10; 100a, 100b); and characterized in that the transmitting unit comprises a transmitting array for selectively directionally emitting the first signal and is configured to control the transmitting array on the basis of the position information so that the same transmits the first signal directed to the position of the underwater vehicle (10; 100a, 100b), and/or that the transmitting unit comprises a movable transmitter for selectively directionally emitting the first signal and is configured to control the movable transmitter in its movement on the basis of the position information so that the same transmits the first signal directed to the position of the underwater vehicle (10; 100a, 100b). control means for moving the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) in the x- and y-direction on the water surface; a receiver for receiving position information for the position of the underwater vehicle (10; 100a, 100b); a control computer for controlling the control means , wherein the control computer is configured to control the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) such that the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) follows the x- and y-direction of the underwater vehicle (10; 100a, 100b) in the x-and y-direction. wherein the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) comprises a transmitting unit configured to emit a first signal such that a runtime of the first signal can be determined by the underwater vehicle (10; 100a, 100b); wherein controlling is carried out such that the surface transmitter (40a, 40b, 40, 40', 40", 400a, 400b) is positioned substantially perpendicularly above the underwater vehicle (10; 100a, 100b) to emit the first signal substantially perpendicularly in the direction of the position of the underwater vehicle (10; 100a, 100b); and characterized in that the transmitting unit comprises a transmitting array for selectively directionally emitting the first signal and is configured to control the transmitting array on the basis of the position information so that the same transmits the first signal directed to the position of the underwater vehicle (10; 100a, 100b), and/or that the transmitting unit comprises a movable transmitter for selectively directionally emitting the first signal and is configured to control the movable transmitter in its movement on the basis of the position information so that the same transmits the first signal directed to the position of the underwater vehicle (10; 100a, 100b). <EOS>