On first review, this image came across as a little under exposed, but on comment review, it would appear that it is perfectly exposed with a couple of minor issues with over done highlights. A good solid action shot that exposing the myth of hippos being jolly animals with good dispositions. A worthy entry into the challenge. A suggestion for the future would be to use a little more light control and go with area metering rather than spot metering which is usually the problem with an image that has highlights like this.