Buy European

Should you want to travel within Europe once you've made it this far, here's a search tool for all train timetables in Europe: https://fahrplan.oebb.at/webapp/?language=en_GB

(Okay, it's missing Euskotren, in Ukraine it only shows long distance trains, and in Estonia and Latvia only the one international connection is shown. But I think this is the full list of exceptions)

You haven't said anything about practical, so the answer might be to cycle across Alaska, take passage on a sail boat across the Bering Strait, then cycle across Russia to reach the eastern borders of Europe, continue cycling until you reach either Brussels or Paris, then take the Eurostar to London. Cycle from there to a port on the west coast of Great Britain (Hollyhead probably leaves the shortest crossing), cross the Irish sea by sail boat, and you have finally arrived in Ireland for your cycling trip!

N.B. Current geopolitical concerns may impact the feasibility of this route.

It sounds like it’s easier to sustainably travel in the old world.

Unless you're planning a small, well-trained crew, endurance sail that'll take a few weeks, you're probably talking one of those huge cruiseliners (that still take between one and two weeks).

Those things burn so much fuel it's ridiculous. And it's heavy oil, so more pollution than cars or planes.

I'm not sure on my figures here so definitely double check, but last I read about it, a transatlantic cruise would burn 3-4 times the amount of fuel as the equivalent passenger flights, whilst taking 20x the time

I know around Europe there are some travel operators that offer passenger berths on commercial shipping lines. Maybe there are also some trans-Atlantic options?
You probably get a small room, and it’s not luxurious. But compared to the literal hundreds tons of cargo on board your carbon footprint is probably minuscule.

You also get a unique experience about life on board, so that’s worth something as well :)
I had an acquaintance who travelled from Amsterdam to Helsinki this way. She was very positive about the experience.

Though you will have to arrange two separate trips which might be a bit more complicated. Cargo vessels don’t stay in port long enough for you to enjoy a full vacation.

Container ship? The ship would be bringing cargo regardless, so your carbon contribution would be negligible.

In the winter you can trek through the arctic on the ice sheets to Svalbard, which is in Europe

I'll be traveling to Europe soon, and my approach is to do a few things:

• find the most direct flights I can
• I'll actually stay over for a few weeks to visit with friends and family, planning not to travel again for multiple years after this
• while over there, travel by train only
• offset the emissions from traveling (using https://www.goldstandard.org/)

It's not perfect, but it's the best I could come up with.

My friend was planning to sail transatlantic alone on a tiny sailboat. I know he is capable of this mad shit, both in skill and in level of recklessness, but I don't know he did it (he has adhd so hard that listening to his accounts of things happened is a rare and chaotic experience). But from what he said, mortality rate in these single person adventures is non negligible. He was in some sort of chaotic depression mood at that point.

I understand many people in Scandinavia sail to Americas occasionally. There is famous Greta, I think, who did it with a tiny crew? With crew and radios and reasonably sized boats, it must be much safer these days. I don't like traveling myself, so it's mostly second hand knowledge.

If you want to sail, volunteer as crew on a cruiser during a crossing

I should also look at the most fuel efficient air plane model with a direct route.

With basic sailing skills you could probably crew on a sailboat delivery across the Atlantic. I don't think many leave from Canada or even the NE US, so low carbon would be to take a train farther South. Maybe Annapolis but more likely Florida. Look up the Atlantic Rally for Cruisers, they have a return rally in May-ish. A lot of boats will be sailing East at that time.

@Sunshine If you want to have the absolute most sustainable way, then yes, get a slideshow of pictures of Europe that you like and look at them from the comfort of your house. If you would rather look for a way that is also convenient, look for the shortest route of flight between continental America and continental Europe and travel by train outside these (and bike in the city). I'm not really sure which one would it be, though.

A ViewMaster with slides of Europe. Practically leaves no footprint.

International travel is very difficult to do. You might be better off flying and looking to pay a certified company to offset your emissions.