Newt estava ilegalmente contrabandeando criaturas mágicas, e assim usava um método de viagem trouxa. Além disso, muitas de suas criaturas não podiam usar vários métodos de transporte mágico instantâneo.
Pong Maniquiz: Loved the movie. Burning Q from my wife though: How come Newt travels by boat to cross the Atlantic instead of apparating?
J.K. Rowling: There's a limit to how far you can Apparate. Inter-continental Apparition is very dangerous!
Victor: Why couldn't Newt have used a portkey? It can't have been difficult for him to register one since he works at the Ministry.
J.K. Rowling: Consider the effect on the contents of his case...
Vick: Is there some sort of Magical Customs for wizards? Maybe not in the years of the Ellis Island ships, but how about now? :)
J.K. Rowling: Newt went in through the No-Maj customs because wizards wouldn't have been so easy to fool. Transporting those creatures was illegal.
(Twitter)
Why couldn’t Newt just Apparate to the USA? Why did he go by boat?
Apparition becomes increasingly risky over long distances. As with most magic, much depends on the skill of the spell-caster: Apparition requires knowledge of the terrain to which one is moving, or the ability to visualise it clearly. Cross-continental Apparition would almost certainly result in severe injury or death.
Moreover, the beasts in Newt’s case had varying magical natures. Some could have Apparated with him, but others could not.
Why did Newt go in through No-Maj customs?
He was transporting magical creatures at a time when this was illegal. No-Majs were far easier to fool than the wizarding checkpoint would have been.