Do native English speakers from different countries understand each other smoothly?

In Japan, people use different dialects depending on the region they are originally form and the same thing is true in other country. Today, I would like to get an answer of the topic "Do native English speakers from different countries understand each other smoothly?". It is apparent that people from different regions speak in a different accent and use unique slangs, but does it make them difficult to communicate with each other? If you have any idea, please share on this forum! Thanks :)

Generally speaking, yes. I mean, I'm from the US and understand people from Canada, the UK, Australia and NZ very well. Sometimes a strong regional accent will throw me off, but it's pretty rare. Philippine English is easy to understand, but English from the other former UK colonies like India, Singapore, etc can be much harder to understand.

I would say I acquired my English mainly from US influence, and I have been able to communicate effectively in rather interesting places. I spoke with Iceland natives pretty good without a hassle. While in Berlin my roommate and I spoke English, and I am sure that she learned it in Germany and not England or the US. Similar experiences in Canada.

I find it pretty interesting. I think England is pretty famous for having colonized a great part of the world, and the US played its role by influencing so much globalized media in the last century. I wouldn't say all English regions talk the same, but I am lead to believe the language is pretty homogeneous, mainly in developed countries, given that is used so much by so many people in similar manners.

If you are interested, do some research on Belize. They have a dialect that is a mixture of English and Spanish (I think) and also a heavy accent. That's pretty neat! 

I think that just like in most other languages, the standard, more refined or ‘educated‘ regional variants are mostly mutually intelligible. But saying that most English varieties are homogenous is a bit far fetched in my opinion. I think that illusion is due in part to the big influence of Hollywood and American media and culture in general. Take a look at this video for example. These are just impersonations but most of them are quite accurate.