Method and apparatus for monitoring the environment of a vessel

A method for monitoring the environment of a vessel provides a liquid (18) which may contain particles (20) in a vessel having containment walls (12), where a hollow member (26) such as a thin tube is inserted into the liquid near the containment walls, and the hollow member contains in it a robotic device (34), which can travel within the hollow member and which can emit and receive ultrasonic waves and electromagnetic fields, where both of the ultrasonic waves and electric fields can pass through the hollow member (26) to the containment walls (12), where the device: emits and receives low frequency ultrasonic waves to and from the containment walls (12) and high frequency ultrasonic waves to and from any particles (20), and emits electromagnetic fields to the containment walls (12) or their combination, where absorptions and reflections from the hollow member walls and the containment walls, and any particles present are measured and any current generated in the hollow member walls and the containment wall by the electromagnetic fields are measured, and then any differences are measured to determine flaws (24) in the hollow member and containment walls, and properties of any particles (20) in suspension.