Here is a cool submarine toy that you can control with your smartphone. Quest happens to be an app-enabled submarine that can cruise on land and dive into water. It has a LED supported camera to capture footage underwater. You get depth control and can use your Quest at the beach or in the pool.
Quest is made of plastic and silicone. It measures 6.25” W x 5” H x 10.5” D. Makes a great gift for kids. Another cool Quirky project.