This colourful little animal is a Jervis Bay Tree Frog (Litoria jervisiensis) with a body about 30 mm long. These are native to the south east coastal area of Australia.

I found the frog floating in my dogs' water bowl, from which it would never have been able to depart. After I took these images (see also PiP), I took it out and it hopped away. Some reflections in the water around its head.