Of course, crossing the Atlantic today is as easy as a plane ride, but it was much more difficult in colonial times - even though I imagine the tiny food and cramped conditions and likelihood of sitting next to a fat man for many hours were pretty much the same.
For European travellers it was at best a six-week voyage - but depending on delays it could last months. Dangers included storms (and their opposite, being becalmed) seasickness, food running short and dying of boredom because you had nothing to do all day.
For Africans captured into slavery, the Atlantic voyage was much worse - across the "middle passage", usually to the Caribbean. The journey was just as long, but slaves were kept below decks and rarely allowed out in the fresh air - with the men usually in shackles. They were given only one meal a day - less if provisions ran low. Disease was rampant, and mortality rates were high.
I will never complain about being inappropriately touched by airport security again. Though to be fair, we're now firm friends, and Juan was very gentle.