“Well, unless someone has some brilliant idea, one of us is going to have to swim down and get the thing.”  Nasaar observes.  “I am wearing armor that would limit my ability to swim, so I don’t think I am the correct choice.”  He looks to the others, frowning as he notices a couple have slipped into hiding.  “What are you guys hiding from?” He calls out to them.  “We need to get the apple, not hide from it...”

Sylvester steps out: “it’s alway better to be unseen just in case. I can try to swim out to it, but we’re not sure what else is out in that water.”

(Are...are you really shouting out while your head is submerged?)

Even with Kastor half gurgled shout, there is no response. The object keeps just whizzing back and forth.

(Yep. Kastor is going to stick his head right under the water and call to the creature.)

"Well, I don't think it can understand me. Do we need it alive, or dead?"

“Well I can tell you I have no clue how to get that thing from deep in the lake.”  Nasaar says with a glance to the creature in the water.  “None of my magic is good for this, and, with the armor I am wearing, I would just sink if I tried to swim to it.”

"Most of my magic is fire based. Not generally effective against underwater creatures. Let's see what happens when you try it the hard way..."

Kastor dives in to the pool, and will try to swim down to get a closer look, at least to see how big it is.

Sylvester follows Kastor in to the water not wanting him to go alone 

(Alright, so Kastor has 4 minutes to hold their breath and Sylvester has 3 minutes to hold. Both of you can only advance 15 feet each 6 seconds and the apple is moving 45 feet in random directions)

On the surface of the water, it is calm but as both of you descend you feel a pull upon your body.

If both of you continue, make an athletics check, DC 15, if fail then you get caught by the current, if pass then you power through it.

The current is random so it'll be decided by roll after the check.

Kastor notices the current, and feels the need for some extra Guidance. (If you're OK with Kastor casting guidance on himself at this point? If not, he'll probably decide against continuing. He wouldn't fancy fighting the current without Guidance).

How far away is the apple? Can Kastor tell if it's actually swimming under its own power, or, now that he's experienced the random current, does it seem like the apple is drifting about, borne on the current?

(Casting Guidance requires verbal so it won't be possible in the water but before hand is okay.)

The apple is drifting about on the current, it does go upward but not near enough to the surface. The apple's direction is random as it's light nature gets it swept into new and old currents.

Then Kastor will continue to go for it. Athletics: 5 + 1

(For 1 the current pulls downward while 6 pulls upward. 2,3,4,5 is N,E,S,W. The only exception is the first roll, you cannot go upwards as there are no upwards current near the surface.)

Kastor is pulled 15 feet 6

The apple is pulled 45 feet 6

(Sylvester does not need to breathe as part of his subclass)

athletics: 13 

(Ah, missed that part)

Sylvester is pulled 15 feet 6

(So potentially we have 40 rounds of this before Kastor runs out of breath?  Are we making Athletics checks per round?  Do we know where each of us are in relation to the apple?  For example, I just moved in the opposite direction to it, but did I get 60ft closer, or 60ft further away?  Presumably there's also still some vertical distance?)

In case you need another athletics check: 20

(Essentially yes, there is also the possiblity of getting stuck in the underwater tunnels, as Sylvester did just get pulled underneath the party. The apple shines brightly for 90 feet so it's 90 feet deep. For trajectory, I'll assume the both of you dove near where it was last. So you'll be 90 feet away at the start, then the round happened. Kastor is 15 feet deep but pulled opposite of the apple direction, so there is now 120 feet between you. I just need to track the apple's elevation and distance from each)

Sylvester, you are pulled back towards the party and is currently underneath them with the cave blocking the surface of the water.

(So basically, the only dangers here are suffocation and getting trapped in the currents. Heavy armor does affect as more weight means easier descent but harder to get back up. And frankly, I am a bit amazed no one noticed Kierran is not there with you all.)

Kastor is pulled 15 feet 1

Kastor decides the currents are too strong for him and gets out while he's at the top. 

"It'll take someone stronger than me to swim down through those currents. I'm wasting my time drifting about down there, we've as much chance of waiting and hoping it floats up by itself than me trying to get it. I'd run out of breath before I get close "

“Well, if you guys think we have an hour, I can resummon my familiar as something that can swim, and send it down after the apple.”  Nasaar says.  “Though a swimming creature might not have any more luck than you guys were, maybe even less, as they would not be as strong...”

(Sorry, it's been...well, to be entirely frank, a shitty few weeks with midterms and other stuff. I also assumed Kieran was just following along quietly, as it's something a lot of DMs do with NPCs to keep them from taking the spotlight.)

Hari looks around for Kieran, beginning to frown as she realizes he's nowhere to be seen. She begins casting her mind back along the trip to this area, trying to remember when she last saw the half-elf.