If I could only learn one additional language, and I wanted to travel the world, what language would serve me best other than English or Spanish?
By the numbers: French or Arabic, as other commenters have mentioned.
But it really, really depends on where in the world you want to travel. If you’re interested in Asia, for example, neither French nor Spanish nor Arabic will help you much (save for some remaining French usage in Vietnam).
A better answer is: figure out where you want to go, then do the math on what to learn.
Depends on the route you want to take while traveling. For example, if you want to circumnavigate in a sailboat through the tropics, French is a great choice because France includes a bunch of tropical islands:
French is also widely spoken in Africa, IIRC.
There are more French speakers in Africa than there are in France and the French Language Authority is absolutley SEETHING at this fact because they’re losing control over “proper French” and for the first time ever French is evolving like a language should
I wonder if most of those countries people don’t speak either English or Spanish as a second language. As opposed to certain specific languages and countries were most people don’t have or use much a second language like for example in Japan or Brazil
In most of the places French is spoken, it is the second language (instead of English or Spanish). Only place I can think of off the top of my head where Francophones would likely also know English is Quebec and, I guess, France itself.
The other languages in the sorts of places I was talking about are mostly ones like Arabic, various sub-Saharan African indigenous languages, or Polynesian.
Mandarin
Kinda surprised that no one has mentioned sign language. I feel that it’s use cases expand outside the original intent, especially if other people in your circle understand it.
But OP was asking about travelling the world. Sign language wouldn’t help with that.
Sign language isn’t one language. There’s American Sign Language, British Sign Language, Australian Sign Language, Nigerian Sign Language, etc.
American Sign Language and British Sign Language are completely unintelligible to each other.
Basically every country has their own sign language or an imported sign language that became standardized.
But learning any sign language will make it a lot easier for you to communicate with signers of any sign language. Not because they’re necessarily similar to each other, but because sign language varies a lot regionally anyway (and even locally depending on what method of signing you’re taught) and it will be much more natural to find ways to work around it and communicate with each other.
Python
