Possible answers:
[+] soundwaves
[+] rubber balls
[+] submarines
[+] whale bones
[+] electricity
[+] rays or beams
[+] light
[+] satellites

Fact 1: Sonar is used to find the location of an object. Fact 2: Sonar bounces sound waves off the bottom of the ocean. Given the two facts above, what can be bounced off the ocean floor to located objects?
Answer:
soundwaves