Meet the Seandragon XLR: an underwater ROV platform with modular components that lets you take on challenging missions in any body of water. It has a control board compatible with ArduPilot. Seandragon XLR can operate underwater for hours and dive to 300m depths.
This ROV has 6 x TT-100 thrusters. It can be upgraded with a robotic arm kit to handle sampling tasks.