I received an email from a student at upr.edu. He wants to be my Ph.D. student, because he is interested in physical oceanography.
There is nothing wrong with wanting to come to Hawaii to study physical oceanography. In fact, U. Hawaii is a great place to study oceanography, not just physical oceanography.
So, I replied as follows.
Richardo,
I think you will better your chance by checking out the person's profile first.
You go to the department's web page, check out each faculty's background, etc. When you write to him or her then, your email will be taken more seriously.