This is another challenging exercise, especially if the pool is shallow. Try to tie a knot in your tether by making a loop, crossing over your tether and then going down through the loop. You can also try going under and coming up through the loop depending on how the tether is floating in the water. You may need to dive and pull some tether deeper since it will likely tend to float slightly. Once you have tied a knot, try to untie it by reversing your course.

Once you master tying a knot, you can try to simulate a stuck and tangled tether. A pool chair or something similar can be used as the basis for getting the tether wrapped around something, and the challenge is to untangle the tether and free the ROV.

If you have groups, a fun challenge is to have one group try to tangle the ROV and then the second group needs to untangle it. You can make this competitive by timing the event for each group or just for fun.