Quote (Quontex)
Possibly an echo location method could also be used in this environment.
Yes. I feel sorry for those beings - they will never see stars, planets, galaxies, nebulae, dawn, aurora, clouds, lightning or rainbow... All these phenomena will be purely theoretical for them, as ultrasound or echo location seeing for us. They could build a device that converts a photo into an echo location image, but it is the same as the ultrasound image for us.