Diving in the cenotes is pretty damn awesome though! You just have to make sure to dive the ones that have been explored and have designated routes. My third and fourth dives after getting my open water certification were in cenotes around Playa Del Carmen and that experience was just mind blowing. Would love to do it again.

A friend of mine made a bunch of films about his cenote diving. This one give a pretty good idea of what it's like: https://www.youtube.com/watch?v=99z8JgxdDmc

He also has some amazing IMAX footage of cenotes, among other caves, in his film Ancient Caves, which is still playing on a few IMAX screens, though it's run is mostly over. https://www.youtube.com/watch?v=MSZL9YbXDGs

Thanks so much for sharing this! Quite wonderful. I'd love to go back with my 360 camera to get some footage because flat screen video never quite catches the feeling of being in those kinds of spaces.

> My third and fourth dives after getting my open water certification were in cenotes around Playa Del Carmen and that experience was just mind blowing.

Overhead diving, especially in caves, is extremely dangerous without extensive training. Too many operators down there will take new divers on very questionable “cavern” tours with sections of no natural light / visible exits, single primary lights, and single tanks.

Do your due diligence and remember nothing in the cave is worth dying for.

In the Yucatan most divers consider there to be a difference between 'cavern diving' and 'cave diving'. Cave diving requires extensive training and is very dangerous. In cavern diving you stay within the naturally illuminated part of the cave and, while there might be something overhead of you at periods, you're not functionally farther from a safe exit than you would be at 130ft depth with no overhead. Of course any overhead obstruction is an added risk but that situation happens in regular recreational diving too.

It wouldn't surprise me to hear that some tour operators bend the guidelines but the diving I did there felt appropriately careful.

Cavern diving certification is still a multi day course, open water certification does not prepare you for it. The 130 ft PADI guideline (AOW cert) applies to open water wreck diving and is quickly broken at most sites I’ve seen. Dos Ojos is particularly sketchy. On overcast days it can be impossible to see an exit at several points even when not silted out. Your guides will usually be side mount with two tanks, backup lights, and a safety spool. That redundancy isn’t for you, it’s because they are trained not to take the same risks you are. Caves are pretty awesome though.

In this particular case it was a very spacious set of cenotes with a guiding string along the safe route. So it felt pretty safe. It was also the day after we had done some open water diving so the dive master got a feel for our skills (I would assume) and none of us were particularly foolish. I doubt I'd ever want to go diving in actual caves with anything even remotely tight for space.

Seems like small cave exploration robots are well within reach for current technology.

Any HN billionaire up for funding the development?

NASA worked with a commercial partner to develop the SUNFISH [1][2] for future exploration of Europa. It's been used to explore underwater caves and they have a video showing the generated data from Peacock Springs [3]

[1] https://oceanexplorer.noaa.gov/explorations/22sunfish/featur...

[2] https://sunfishinc.com/

[3] https://www.youtube.com/watch?v=mpKFkrUeF9o

will probably never get those commas, hopefully wont need them because this video by Polish students made one of my 'retirement projects' "underwater ROV"

https://www.youtube.com/watch?v=P2kChvtPxyw

they're hurrying along though https://www.youtube.com/watch?v=VZucylrwaK0

A submarine drone could probably be done as a hobby project with a fairly limited budget.

There already is a company doing this, I’ve heard the CEO speak at a conference. They are heavily involved in the cave diving community and will likely start making long distance mapping records in the next few years.

https://stoneaerospace.com/

How small do you have to be to do this kind of work?

I'm curious, is the theory that Homo naledi carried their dead through that tiny shaft to be buried there or was there another way in?

The lead scientist who discovered it (Lee Berger) certainly thinks they did; they haven't found any way they could have accidentally fallen in from the surface and there are no (or almost no?) bones from any other species. He further claims they have evidence of intentional fire use and rock art.

Approximately every other paleoanthropologist is extremely skeptical of this and also constantly mad him for other things like putting preprints on bioRxiv, having too many TV shows, going to space with fossils, etc.

On the other hand, every paleoanthropologist except him seems to run on a system where they never reveal any discoveries or share their work with anyone and take 30 years to write up what they have found in case someone steals their dig sites. It kinda seems like he's right.

I'm sorry but I watched enough YouTube to know that out of all ways to die, cave exploring, and especially underwater cave exploring, is not for me.

I am very fortunate and grateful to have experienced this with my family as well.

It was surreal and other worldly to me while swimming underground in crystal cold waters surrounded by fibrous tree roots hanging down from high above. How did these fish get in here?

Roe aka released mature fertilised masses of fish eggs often stick to sea grasses until fish hatch ... buut ...

Given a good tropical storm these get shaken up, scattered about, float to the surface, and get picked up by water spouts, waves, and other events that can carry them into the air and then at the mercy of the winds and sleeting rain movements .. some of which will shed into inland sinkholes, etc.

Further, much of the Southern North American and Central American land form is crossed by limestone and and underground river systems that are fed by water above ground; where water flows eggs can follow.