Here is another underwater drone that you can control with your smartphone. The Chasing Dory is a lightweight ROV with a WiFi buoy to connect to your device. It also has a 50ft tether. You can control this underwater drone to your mobile device from up to 50ft away.
Dory comes with a 4800mAh battery. It has max speed of 1.5 knots. It is rated for max depths of 15 meters. The battery lasts up to 60 minutes.