For this exercise, you will need something like a hula hoop, weight and float. Tie the weight and float to the hula hoop so that when placed in the water, the hoop will be suspended in the water column. If you have manipulator you can use it to retrieve the hoop. If you don't have a manipulator, you should add an additional lead so you can retrieve the hoop from the shore.
While navigating, try to penetrate an opening without hitting it with the ROV. Practice going forward in, turning around and forward out, as well as forward in and reversing out, and finally, reversing in and forward out.