phd abroad


I am currently about halfway through my Masters by Research program and am playing with the idea of doing a PhD overseas once I am done, either to completion, or perhaps doing part of a PhD overseas, if that's a option. I know I can look up rankings of uni's and what they have available etc. online but I'm looking for some personal experiences from people who are doing this themselves.
I am thinking maybe America as an option? However does anyone have any recommendations for countries/uni's or advice/experiences that they would give?
I am particularly interested in studying marine animals/mammals if that has any impact on my decision.