There are nearly 400 million speakers of Spanish in the world. Many of them are spread across the 21 countries where Spanish is an official language (indicated on the map above), but there are even more people who speak it as a second language, especially in Europe, the US, and other places around the world. Sure, there are other languages with more speakers, but besides English I think you'd have a tough time finding another language that is spoken so widely across the globe. (For example, Mandarin has nearly a billion speakers, but they are nearly all in just one country--China.)
Speaking Spanish can help you make much deeper connections with people on your travels. Knowing the local language is always a plus, as it makes it easier to navigate, experience daily life, and make friends. Spanish, though, is especially useful. In a lot of places in the Spanish-speaking world, finding an English speaker is pretty rare. Especially in Latin America, people prefer to speak Spanish for personal relationships or business. I'd heard from friends who went to Germany to learn German that all the Germans there would automatically switch to English so they could practice; this sort of thing is much less common in Latin America, so Spanish is very useful! People in most Spanish-speaking places are also very willing to help you practice Spanish and appreciate the effort you're putting in.
All the romance languages--the ones descended from Latin--are very closely related. Check out the collage above, which has the word "travel" in various languages so you can see the resemblance. Learning Spanish can help you learn other languages later, such as French, Italian, Romanian, or Portuguese. It can also help you understand scientific or medical names, which generally use Latin, and Spanish overlaps with Arabic, another really useful world language. Because Spanish is so closely related to other languages, it can give you a great way to fake it 'til you make it. When I was in France, my knowledge of Spanish helped me understand some of the signs and directions a little better, and recently when I was in Canyonlands National Park I could understand a good 60% of what a group of Harley riders were saying--it turned out they were speaking Italian!
Spanish is one of the most useful languages in the US, so it'll likely help you at home too! When I worked in customer service they were happy that I had that skill and I was able to interpret for Spanish-speaking customers on occasion. I also have a mentee whose family is from Mexico. Her mother only speaks Spanish, which is a large reason why they paired us together. Without my Spanish skills, I never would have met her and had so many great times with her over the past four years!
The Foreign Service Institute ranks Spanish as a Category I language. This classification is for "Languages closely related to English" and is the easiest category, with an estimate of 23-24 weeks to reach general proficiency. Additionally, in the US there's a lot of Spanish-language influence and so many resources available! You can change the language on most of the DVDs you own to Spanish for practice, there's plenty of great Spanish music, and there are a lot of speakers in the US to practice with too!
Spain and Latin America have produced some amazing literature, art, and film over the years. Just think Don Quixote, Pan's Labyrinth, or Guernica by Pablo Picasso. Experiencing them in the language they were written/created in can enrich your understanding of them greatly. Plus, Spanish art, architecture or literature could inspire your next trip!
If we consider reason #1 again, the it's obvious that there are a lot of destinations where Spanish is useful. Perhaps not so obvious, though, is the wide variety of amazing things in those locations. Knowledge of Spanish can help you explore a medley of Mayan ruins, old forts, Spanish colonial architecture, palaces like the Alhambra, rainforests, Machu Picchu, gorgeous beaches & more!
Between the fiestas and siestas, the paella and chimichangas, Spanish is a really fun language to learn! There are so many cool cultures you can experience through the language, and along with Spanish you'll learn about interesting traditions, hear great music, and maybe even eat some new foods. Plus, Spanish sounds great and is fun to speak--just try rolling your "rr"s. This isn't to say that other languages aren't fun, but I'm not sure how many could claim to be more fun than Spanish!
How about you? Do you speak Spanish? Would you like to someday? What do you think are the most useful languages for travelers to speak? Comment below!