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Second massive “blue hole” found, 270 metres deep (popularmechanics.com)
55 points by bandibus 1133 days ago
10 comments

What is it with those weird metrics? 147,000 square feet across, this is what science communication picks up from the paper?

The major axis of the TJBH at ~10 mbsl was estimated to be ~151.8 m and was oriented ~10.76° clockwise from the north, similar to the main direction of geological faults in the region. The minor axis, perpendicular to the major axis, was ~124.4 m across. The surface area covered by the blue hole is ~13,690 m2 (1.4 ha) with an external perimeter of ~492.7 m. The structure of the blue hole can be described as a conic shape that is north-skewed with a volume of ~1 million m3.

Why not about 140m (450 ft) diameter?

The full open access article is here:

https://www.frontiersin.org/articles/10.3389/fmars.2023.1141...

The conversion from square meters to square feet is 13690 * 3.28 * 3.28 = 147282.496, so at least it's the correct number for area. But yeah, adding "across" sounds weird there.

Edit: Actually for a much easier visual, it's right about 2.5 American football fields.

> a much easier visual, it's right about 2.5 American football fields.

One that means absolutely nothing to the majority of the people on the planet.

It's about one Australian Rules Football ground
I think it was a joke. But I’m not sure.
Not a joke, the article converted from meters to feet so the demographic limitation is ~the same. Don't know why the title on HN uses metres, the original title doesn't have any size.

I only included "American" because I knew someone would jump on it with soccer/non-American football fields.

Alright. The American obsession to use random things instead of the international system of units is weird and funny so I thought you were joking about it.
> I knew someone would jump on it with soccer/non-American football fields.

There is no such thing as "soccer". The correct name is "football", because you use your feet to move the ball inside the field during the game.

There is also American football, which is an entirely different game, that's neither played with feet, or a ball.

;-P

And to a lot of Americans also.
To clear things up, then, it's about 1.64 Canadian football fields.
I can’t possibly visualize its overall Size without knowing how many Olympic sized swimming pools it could fill.
I need more granularity to get a sense of the volume we're talking about here. Has anyone measured it in double-decker buses yet?
Large MLB fields are in that size range too: 400+ feet across dead center. https://www.si.com/mlb/2021/03/24/mlb-outfield-walls-ranked-...
I think the main point was the measurement of area 'across', not the non-SI unit.
The article converted all the measurements for a US audience, but the "square feet across" line halfway down is the only one they jumped on. Plus questioning why not just use diameter at the bottom of their comment.
We agree then?

Edit: Oh wait, sorry, I must have misread/not read that you agreed adding 'across' was weird initially. Thought you were just saying 'sqm/sqft no big deal move on' sort of thing.

> Edit: Actually for a much easier visual, it's right about 2.5 American football fields.

OK, but how many elephants would that be?

Somewhere between 1291 and 3506 adult African elephants from the measurements I found.

;D

What's the conversion from African to European elephants?
It's not just "weird" -- it's completely nonsensical. It's like saying "the color of a stop sign is triangle"
Absolutely. Everyone knows that the colour is octagon, by international standard. (-:
Or ~147 avg house footprints
Average house sizes vary wildly (>2x) across countries.

For the US it's 201 m2, whereas in Ireland it's 89 m2.

Yeah I was going with sqft —> US houses.
"Tim Newcomb is a journalist based in the Pacific Northwest. He covers stadiums, sneakers, gear, infrastructure, and more for a variety of publications, including Popular Mechanics."

Could be why.

Worth pointing out, the image in the article is actually of the 'Great Blue Hole' off the coast of Belize, which is about twice the diameter but half the depth[1] of the one in the paper.

Also quite the opposite of 'recently discovered'; it has been one of the best known diving spots in the world for over 50 years, and one of the very few ocean floor features that I can recognize by eye...

https://en.wikipedia.org/wiki/Great_Blue_Hole

What is it with articles like these still using language like "discovered"

> Guided by tips from fishermen, scientists from Colegio de le Frontera Sur explored a tropical estuary off the southeastern coast

> the scientists names their new discovery the Taam ja' Blue Hole, using the Mayan language phrase

Clearly the locals have known about this already. If your argument is that the difference is when it's published in some scientific paper then that's also contradictory to:

> the new blue hole was discovered in 2021, the researchers only recently detailed their findings in a study published in Frontiers in Marine Science

"Discovered in 2021" pretty obviously means Western people here. If it was about "scientific description" then we would've said 2023.

It reminds me of that one white person that traveled to Mexico and "discovered" a variety of corn that produces a mucus-like goo that traps nitrogen from the air itself instead of using bacteria. This variety had an indigenous name and the people who've been growing it for thousands of years could trace back their entire lineage of people who've developed the variety specifically to grow in those low-nitrogen conditions

Yeah talking about discovery is weird. The title even says it "just showed up" making me think there was a geologic events involved.

Though I wouldn't dismiss any relevance of the year 2021, as that was when the scientists did their field work. Imagine another team did study the same hole in 2022 but published earlier, then that would be relevant.

Because its depth was discovered by researchers in 2021.

The Mayans knew that it was a blue hole. They didn't know that it was among the deepest known in the world, simply that it was one of many blue holes.

> Clearly the locals have known about this already

Clearly they knew there was a small patch of deep water. Maybe not much more than that. I think you're being way too quick to jump to self righteousness

>Discovered in 2021" pretty obviously means Western people here. If it was about "scientific description" then we would've said 2023.

If the meaning is clear what seems to be the problem? It seems like manufactured outrage to be upset by this. I just discovered fuente avocados last week. I'm not claiming to be the first human to ever behold them.

As a thought experiment, can a secret never be discovered?

On the facts of the story, it seems highly unlikely that the locals knew that it was the second deepest blue hole on the planet.

The meaning is not at all clear. The only definition consistent with this set of facts is "a Westerner found out about it". No paper was published in 2021
The very first line is this:

"Scientists have released a study of their 2021 discovery of the world's second-deepest blue hole off the Mexican Yucatan Peninsula coast."

I wasn't the best at grammar, but I'm pretty sure the word "their" refers to the scientists, who found it in 2021.

Who did you think the article could have been talking about discovering it if you were so confused?

My guess is you knew exactly what it meant but were triggered and looking for something to be offended about.

To press the issue, how do you feel about Columbus discovering North America? Keep in mind no one has ever claimed that Columbus was the first human to lay foot in North America.

I'm finding it hard to believe you're not screwing with me now...

Is this a joke? Am I missing some kind of joke?

If not can you please link me the 2021 academic paper in which this was described.

Hint: it doesn't f*cking exist

Very cool. I will note that it is significantly less picturesque than the stock photo used in the article.

https://explorersweb.com/taam-ja-blue-hole-mexico/

Thank you! I could definitely have picked a better writeup of this story than the PopMech piece, and this link is much better. Cheers for that.
What makes blue holes so fascinating, in my opinion, is the historical perspective they provide.

These were once deep air-filled vertical shafts, formed by the longterm erosional/dissolutional power of falling water under the influence of gravity. Speleothems like stalactites prove that they formed in an air-filled environment.

In other words, the present-day sea level at the Yucatan Peninsula was formerly at least 275m lower; and/or the present-day surface was at least 275m higher. The paper attributes this to "glacio-eustatic changes", which is the equal-and-opposite-reaction involving lowered sea level (increased global glaciation) and the buoyant rising of the regional continental crust since the mass of additional sea water has been removed.

I'll see your blue hole and raise a "Blautopf" near where I grew up:

https://en.wikipedia.org/wiki/Blautopf

Rayleigh scattering on nanoscale limestone particles!

> Our knowledge of blue holes is limited by accessibility issues, sometimes due to opening being too small or the depths being so great, and sometimes due to limited oxygen in the water, making it dangerous to explore without specialized equipment.

I'm curious why lack of oxygen is a problem? We don't breathe water, so why should oxygen content matter?

Not sure if it's the case here but typically a low o2 underwater environment means a high concentration of Hydrogen Sulfide. This can have corrosive effects on some scuba gear and generally makes visibility very poor. I've crossed through a H2S layer in a Mexican Cenote (fresh water on top, H2S in middle, Salt on bottom) it was only a few feet thick, it's not something I'd want to spend a lot of time in though. Even though you are on SCUBA you can still smell and taste it and it's not pleasant.
Right, any explorers would dive with their own breathing gas. The actual risk in some of those blue holes is not low oxygen but high hydrogen sulfide.
At first I assumed this was the one near Belize, which is quite well known in the scuba diving community [1]. In fact, the picture on this post is probably of that one. However, this new one is over twice as deep!

[1] https://en.wikipedia.org/wiki/Great_Blue_Hole

Google maps - https://goo.gl/maps/DddfusRBWZ6WtCV19

Easier to see on Google Earth on a less windy day. Search "Taam Ja’ Blue Hole"

I hope they sterilized all the equipment before lowering it into the hole... Surely?