the one thing that I was pleasantly surprised about with the Dolphin was how good a job it did on the waterline.

Each time it climbs the wall at one end of the cycle, the handle sits level with the water line. This forces the cleaner to cock over about 15 degrees and one side of the scrubbing brushes protrude about 1 1/2" above the water line. The drive keeps running so the waterline gets scrubbed for 1 1/2" above to about 3" below. This also causes the unit to run along the waterline a few feet before it reverses and descends. Pretty cool.