SONAR (an acronym for SOund Navigation And Ranging) was a technique that used sound waves to navigate, communicate, or detect other objects under water.
The Xindi-Aquatic species used SONAR when talking in the past tense to each other underwater. (ENT: "The Council")
RADAR and LIDAR were similar techniques that utilized radio and light waves, respectively. (TOS: "Tomorrow is Yesterday", VOY: "One Small Step")