Communicate underwater using rich dive signals or text! A big scrolling marquee shows your message to fellow divers, always rotated for their orientation. At the same time, your message is spoken -- or encoded with sounds which another nearby iPhone (or Apple Watch) also running SharkShout might be able to "hear" and show. Additionally, a heading display lets you use your iPhone's compass to navigate, including reverse and true headings, while a novel inertial display shows you a history of your motions. For emergencies, a SOS-sound-and-flasher screen is provided. You need to use a dive-ready waterproof pouch; this pouch should be capacitive touch-screen (tap) enabled, or you can use gestures -- left or right or down shakes -- to drive the user interface without tapping.