If you're full cave and trimix (including helitrox) you can dive eagle's nest according to park rules. I say according to park rules because you are supposed to check in online nowadays (but it seems nobody actually does) and while you're supposed to be trimix certified I see alot of cave divers not trimix certified dive it. They shouldn't at risk of getting the cave shut down. I will say I've seen less OW divers there since the check in process started at least.
As for the site I won't go too into detail, but if you have the requirements you can absolutely do a "cavern" dive although it's really cave at many points. A "cavern" dive at EN would more correctly just be referred to as diving the ballroom. I have dove EN many times, but have never done more than the ballroom. I'm only helitrox certified and it would quickly get too deep for my cert level if I attempted to go any further and isn't worth it considering how little cave I'd actually get to see. There is a line that goes from a big tree branch at 20 feet down (where you can leave your deco bottles)through a solution tube into the ballroom. The line drops down to the debris mound at 130-140ft depending on water level. From there the line t's to the upstream and downstream lines. On good days you can see sunlight from the solution tubes, on bad days you can't. It is a huge room and it eats your light. It can be a little overwhelming your first time. Once down in the shaft our typical dive plan is to head down towards the mound level and then swim circles following the walls while slowly ascending. There are tons of fossils to see. On a typical or crappy EN day you can't even come close to seeing from one side to the other. Good days you can. Also sometimes it can be hard to see the upline from far away but it's not like it's easy to lose either.
Everything I posted is easily found on the internet, so I'm not giving any details that would be encouraging to non-certified divers or wouldn't be deemed koisher. If the OP is truly cave certified (and some form of helium certed as well) give him a break because he's just looking for info. I ask people for specifics on caves I've never dove all the time. Just because it's EN doesn't mean we need to give him a hard time.
I would highly suggest going with someone who's been before for your first time. It's not a necessity, but it is smart. If cionditions aren't perfect then having someone who knows the site to give a little guidance is nice.
It also gets very hot there. The sun beats off the ground. I always recommend a collapsible cover if you have one.
As for the site I won't go too into detail, but if you have the requirements you can absolutely do a "cavern" dive although it's really cave at many points. A "cavern" dive at EN would more correctly just be referred to as diving the ballroom. I have dove EN many times, but have never done more than the ballroom. I'm only helitrox certified and it would quickly get too deep for my cert level if I attempted to go any further and isn't worth it considering how little cave I'd actually get to see. There is a line that goes from a big tree branch at 20 feet down (where you can leave your deco bottles)through a solution tube into the ballroom. The line drops down to the debris mound at 130-140ft depending on water level. From there the line t's to the upstream and downstream lines. On good days you can see sunlight from the solution tubes, on bad days you can't. It is a huge room and it eats your light. It can be a little overwhelming your first time. Once down in the shaft our typical dive plan is to head down towards the mound level and then swim circles following the walls while slowly ascending. There are tons of fossils to see. On a typical or crappy EN day you can't even come close to seeing from one side to the other. Good days you can. Also sometimes it can be hard to see the upline from far away but it's not like it's easy to lose either.
Everything I posted is easily found on the internet, so I'm not giving any details that would be encouraging to non-certified divers or wouldn't be deemed koisher. If the OP is truly cave certified (and some form of helium certed as well) give him a break because he's just looking for info. I ask people for specifics on caves I've never dove all the time. Just because it's EN doesn't mean we need to give him a hard time.
I would highly suggest going with someone who's been before for your first time. It's not a necessity, but it is smart. If cionditions aren't perfect then having someone who knows the site to give a little guidance is nice.
It also gets very hot there. The sun beats off the ground. I always recommend a collapsible cover if you have one.