A navigation system includes a support structure configured to be positioned at a sea floor. The navigation system also includes multiple transducers coupled to the support structure at fixed locations and configured to emit multiple reference signals. The navigation system further includes a transducer coupled to a movable subsea vessel and configured to receive the plurality of reference signals. A controller includes a processor and a memory, and the processor is configured to determine a position of the movable subsea vessel relative to the support structure based on the multiple reference signals.