I must admit, I don't know very many holidays in other countries.
I've heard of Midsummer, Cinco De Mayo, Canada Day, Bastille Day. If others are listed they may jog my memory, but I don't know them off-hand.
I've totally heard of Cinco de Mayo -- and even know what date it falls on!

Oh but wait, do I know what it celebrates? Nope not really. Something to do with Mexican independence from Spain, I'm guessing. Sorry, Mexicans.
I don't know when Canada Day is or what it celebrates. Sorry, Canadians. I've heard of Boxing Day, and isn't that the day after Christmas? It used to remind me of the sport of boxing, but then I came to think it's something about boxing up your gifts or throwing the gift boxes away. But that's probably not it. Sorry, UK residents.
I do know vaguely what Bastille Day is (something about storming the Bastille in the French Revolution?). But I never remember what the date is, or think about it more than once every five years or so. Sorry, French people.
Midsummer, however, is one where the date and reason for celebrating are both pretty obvious. As a child, I read a book by a Swedish author set in Sweden in which children celebrated Midsummer, and it sounded really fun. As another resident of a far northern latitude, I can totally relate to the idea of celebrating the solstice. Yay, Scandinavians!
For years I've been under the impression that the traditional refreshments for Midsummer were crawfish and ice-cold vodka. That's because when I lived in New Orleans I wrote a newspaper story about China trying to overtake the crawfish industry by deliberately selling crawfish at below-market rates. (My spellcheck is telling me I'm supposed to say crayfish but in Louisiana they call them crawfish.) I learned that Scandinavian countries were the biggest crawfish importers, and somebody said they eat them at Midsummer with vodka.
That sounded delightful to me. And I just googled now and found that there IS a holiday in Scandinavia where they consume those things. Only it's in August.
Yep, I'm one of those ignorant Americans.
Chrissi and I have been trying for years to promote a holiday called Longerdays, the day after the Winter Solstice. It hasn't caught on really widely yet but at least we can say it's celebrated internationally!
(In truth, I think we already have one or two winter solstice celebrations -- they're called New Year's Day and Christmas. I'm pretty sure the dates designated are related to their proximity to the solstice, and in the case of Christmas the willingness of early Christians to meet pagans halfway on holiday traditions.)