Studying in the USA as a non citizen

[everymeeveryyou]

DS3 is in Y12 and after asking him to narrow down Unis for visits he has presented me with an option of studying in America instead. 2 of his siblings have been through/are going through the English Uni system and I am looking for advice on what to consider and expect if we support his request.
He is looking at Marine Biology in Florida or California.
Currently DD is in London so we are already experiencing the cost of that, but am aware that US universities are much more expensive.
Any advice, signposting or information would be gratefully received.

I'm sorry I misunderstood you!
I just thought you were responding to someone who was saying UK students haven't put much thought into the process, by reassuring them that the SAT is not hard, which is true, but not the most important part of the challenge of this application process...

My son, with 4 A* and 2 A grades at A level, an SAT score of 1580, top ACT scores (as well as lots of other good things, hobbies, etc) still got rejected from 3 of the 5 US universities he applied to.

Lots of people in the UK think that the SAT is more important than it is!