Out of Character

If you equate that fact to a Hunter Shark, a large creature and it being marked as a "temporary excursion" I would take difficult terrain with swim speed. Impossible without

That is certainly a creative use I have never thought of! Hmmm....for a size small I would say yes... for a size medium maybe... and size large no... how about force an athletics or acrobatics check and if successful make it difficult terrain.

Not acrobatics, athletics covers swimming.

That said, I don't think swimming up it is an option. It doesn't counter gravity, which would still be pulling you down. But that's just my take.

It would be like climbing

I agree about athletics. As far as the swimming up, we do that when we swim up in a pool from the bottom. My concern is how the wall is 1 foot thick and how that might be too small to swim in.

Maybe I'd require an athletics check DC 15 with disadvantage due to the thin water to do it. On a failure, the spell is still there but you wouldn't move very far. Not sure if having a swim speed would affect that though.

Also things float up

But only because of water displacement/bouyancy. If I climb on a roof and run a hose on you, you don't float up.

The hose is also flowing down, while this spell doesn't say anything about the movement of the water, so that makes me think it is still like a pool with no wind

Except the flow isn't what's preventing you from floating.

did I get an opportunity to do a AoO with my PAM strike when she went to attack me? If not. I am down and making death saves

I think a lot, perhaps too much, so feel free to ignore any of that

But there is a rule of thumb - when in doubt, let the dice decide. Maybe a PC run even (not swim) up a 1 inch thick water ... why hot if he roll 100 on 1d100?

Snakey hair has a reach of 10 feet. her movement didn't provoke opportunity attacks, but if polearm master is triggered by her entering your reach, not by opportunity attacks, then yes you can get an attack off before you would have been hit.

verbiage of the PAM ability....don't think it will work

Sounds like no, then. I think in the 2024 revision, they are changing that language to make it not an opportunity attack so it doesn't become such a powerful combo with sentinel, which would also mean it would have worked here, but we are using the current version 2014 so I have to think no unless someone sees something I don't.

If somehow we have a one shot with 3 different Nat20's on Death saves...that would be wild

Just to make everyone aware, I am hoping to do more one shots like this in the future. As such, especially with how this is going, I'd want to get feedback from everyone to see if I can make the next one better. As for feedback, I see 3 options:
- Public: I make a thread just for feedback and people give their thoughts. everyone knows what was said and by who, and thus can piggy back or add to comments. However, some people may not be as honest if others can see what they say beyond me.
- Private Subthread: I make a subthread and within it a thread for each player so there can be a 1-on-1 conversation here on the site for later reference by both me and the player. Less public, still allows back and forth.
- Survey: I make a google form and ask everyone to fill it out. More formal, less personal, only I will see the results.

Generally, we could mix and match but I don't know if there is much point in that vs asking everyone to use the same method.

what about a mix? sometimes have a survey then the public forum as well?

Your survey could help provide some context on the questions and styles you are looking for, which could allow for a more public forum being helpful.

I am actually doing this at my job, where I am surveying different departments to see how the last year has gone and then meeting with the individual groups to allow it to be more of a conversation as well.

That is an option. If others agree then I can do a survey and public comment thread

I could only recommend you to try allow everyone use the media comfortable for them, not the one majority vote

If people want to keep what they say private (which is perfectly fine of course), they can always DM you.