What is this?

I was walking down the Iona Jetty in Richmond this past Saturday and witnessed what you see above. the bird had a massive wingspan and flew only about 15 feet away from me. I'm no bird expert but I'm thinking something along the lines of a hawk or falcon based on it's head and size. I'm not sure if the photo does the moment justice but it was an amazing sight to behold. If you have any idea what this bird is, I'd love to know.