Backswimmer or Waterboatman

I found this little fellow on the side of the glass container, about 2.5 cms in length. It is one of the numerous species found in the pond


Class: Insecta
Order: Hemiptera
Sub Order: Heteroptera
Family:Cryptocerata
Genera:Notonectidae

This is how I have identified it as best I can at this stage. Backswimmers are aquatic predators. Or maybe it has me fooled and its a waterboatman. It could be either because when it swims it does not seem to swim on its back.