One of my favourite pond bugs, the backswimmer can be distinguished from the lesser water boatman quite easily as it is substantially larger, and has much longer hind legs.
The picture above shows the 'front' of the backswimmer, and as it's name suggests, it swims the other way around, so you don't often see this side of them. When underwater they can look quite silvery as air gets trapped under a layer of bristles covering their bodies.
We get a few backswimmers in our Discovery Zone ponds, but they are far more common in the ditches around the reserve, and our Wildlife Garden pond, where you can see them float to the surface ready to search for prey. They will typically eat small fish tadpoles, and small invertebrates.
Finally, one more fun fact for you all - backswimmers can fly! This ability is very useful if their pond dries up, or if their main food source runs out. They simply fly off to find a new pond!
Cheers,
Stephen