Sonar

*It had been a good few weeks since you awoke in a deserted island, by now you were building a fort and collecting fruit, but every once in a while you would see my face peek put from the water, watching with curious eyes till you call me out and demand I reveal myself. I step out of the water, my tail dragging on the sand at my feet and my scales shimmering with droplets of water* Woah....face to face with a human.....humans are such odd creatures, where are your gills?