And dous.
I’m going to go ahead and assume you’re saying that some members of the tribe looked European.
Because my first two interpretations of that sentence were actually a little nightmare-fuel-ish, if I’m honest.
I never heard of that one, interesting, but mostly I am so shamelessly going to steal his epitaph for something, I just don’t know what yet.
SKyquakes. Unexplained booms out of no where.
The sound of rolling artillery fire just over the horizon is what it sounds like to me. There was a frisson of panic in NYC in the 90’s when the skyquakes were heard there, but it didn’t seem to last.
There are also underwater versions of this which I don’t know the name of. When I was in grad school I had a professor who was researching the underwater booms (not earthquakes, not explosions, not whales, not anything he’d ever recorded before). We did a lot of signals analysis on them and they didn’t match any pattern, so what the underwater ones were, no idea.
duoe sorry
Unexplained sounds. Most of them are caused by ice movements, but just the idea of these noises, loud enough to be heard from thousands of miles away, coming from somewhere in the ocean, creeps me out intensely.
^^^^^ Post/Username Win! 
^^^^^
Rhymes with ‘orange’.
What is Banksy’s real name?
It’s also not mysterious, at least if you only include the aspects which weren’t simply made up. The most interesting real part, where they were found nude or nearly so, is a known effect of hypothermia.
This kind of stuff rather quickly runs to the conspiracy theory and/or made-up bullshit end of things, including hoaxes well past their sell-by date, such as the supposed Oak Island Money Pit and the Beale ciphers.
Something I’m surprised hasn’t been mentioned yet: Who is running the various numbers stations around the world, and what are they saying?
The most reasonable guesses are, in order, “Various drug cartels and national intelligence services” and “A mix of instructions to field agents and absolutely nothing broadcast to fill time so enemies can’t observe how your rate of transmissions is changing”. So it isn’t a huge mystery, probably: We likely know at least that much, and are now waiting on a mix of declassification and drug busts to uncover the rest.
Various “numbers stations”-like events on the Internet have, so far, all been obviously connected to games or pranksters of various types. To my knowledge, none of the shortwave numbers stations have been.
Or Subcommander Marcos, for that matter?
These threads kind of make me sad; before the internet (or just when I was younger?), there were all kinds of wonderous, incredible mysteries. Now, there’s maybe one or two left, and the mysteries are just about mundane details (who perpetrated the Max Headroom thing?), not things that can’t be explained by our current views of the world (we know more or less how Max Headroom happened). Or the Tamad Shud case: fascinating in the details, but it’s not like a spy and/or disappointed lover killing himself/being killed is going to shake the foundations of physics.
I mean, Oak Island, for instance. It used to be a fascinating story of mysterious technology, etc. Now you can just find an internet page that points out there is absolutely zero evidence of any of the reputed earlier events, and that everything is consistent with it being a mid 19th-century scam to sucker treasure-seekers.
RE: -gry
I think I can solve that one.
The third word is “agree.”
See, it works if you say the riddle out loud. “Angry,” “Hungry,” and “Agree” all have the same final sound, and if the riddle is oral, “agree” fits the bill. It’s only when you write it down, and are suddenly looking for a word that ends in a letter sequence, rather than a sound, that it fails.
It’s a trick in the oral form, because some people think they are looking for the letter sequence, but you never said that, you just said the sound. However, when you write it down, you change it completely. If you try to write the sound out phonetically, it becomes obvious what you are asking, and the person comes up with “agree” right away.
Ooooh! I see The History Channel claims to have found something last year! It would be insanely cool if they actually found treasure down that hole 
I know exactly what you mean, but I take the opposite view: I find it more wonderful, not less, that there are fewer unexplained things out there. It means one of the oldest tasks humanity has set itself to is paying off.
Back in the Neolithic, and likely long before as well, we didn’t have any way to tie most of our explanations together. What was lightning? What was fire? What was the reason some rocks could be crumbled and others couldn’t be? We invented stories, as humans do, but they were mostly just-so stories with no predictive ability: We had deities who did things for their own inscrutable reasons, which made for interesting tales but didn’t give us any way to predict novel scenarios.
Now we have explanations for why things happen, and they show us amazing and previously unsuspected connections between what seemed like vastly different aspects of reality. For example, lightning, fire, and fragility are all tied in to each other through the behavior of electrons. We can draw a line on a page of paper using a pencil for reasons deeply connected to how all of our organs work, and more tangentially connected to how lightning and magnets work. We use these explanations, directly and indirectly, to improve lives, by allowing us to predict what familiar things will do in new combinations, and allowing us to make valid predictions often enough we aren’t just wasting our time.
In fiction, and all of these fake unsolved mysteries are just fiction, there’s figure and there’s ground, there’s the part which matters and the part which is just flavor and setting. Following the part which matters is rewarding, or as rewarding as the plot gets, but trying to go in any other direction gets you a door slammed in your face with no way to open it. It gets you graphics glitching, hollow models, and a skybox enclosing everything, circumscribing your travels. In reality, everything matters, and everything is just as well-drawn. Every atom has just as much of a history as every other, every star is just as much of a star as our Sun, and every person is just as much of a main character as everyone else.
By tying things into our theories, we now get to see a deeper elegance, something far more beautiful than the gaudy sideshows of an Oak Island or the cabinet of horrors of a Roswell UFO crash. We now get to understand how simple rules interact to produce unimaginable variation, complexity beyond our ability to catalog, and we know that it’s all real. It won’t peter out into dead-ends, or reveal plot holes when you press a point. It isn’t just a paper moon anymore: it’s real, and we know it’s real, because we’ve been there.
aggry
The riddle specifies “three common words you probably use every day.”