chatGPT wasn’t as helpful as I would’ve liked.
My fault for keeping the loom window open lol, first time posting on Unreal community 
Hey there @ZahidPlanet! Welcome to the community! So it seems that something is blocking your descent into the water via an actual collision. So we could guess at a number of things, if it’s the water or some invisible plane, etc. But we can just as easily check what the player is colliding with. (Could just be the water, but this is a teaching moment).
So slide into your character class and make sure it’s capsule collision is set to generate overlap events and hit events. Then pop this little print statement in there like so and run the game, hop in the water and see what prints out.
It will tell you which actor it’s hitting, and on that actor we’re going to check in it’s collision details what type of collision it is, and either change it, make a new one, or change the settings in your player to ignore that specific collision layer. (Caveat, if you want to swim and not fall and walk on the ground at the bottom, this will be a bit different).
The Fishbowl
So technically making the water not enter the pod is not going to be an easy process nor do I have too many resources to get you there.
Generally speaking, the water you’re seeing is really just a very fancy plane mesh. There’s lots of operations happening to this fancy plane mesh at any given time. Though it’s just a plane so it doesn’t really have the functionality built in to “fill” or respect fill boundaries of meshes inside of it. You could use an exclusion volume for the water, but that can’t be moved at runtime.
There are however ways to fake it with materials, but I am by no means an expert in that field. As you can see the glass itself actually obscures the water in it until you look from a different angle so pushing that one step further by closing your mesh at the mouth but having a transparent material that blocks other transparent materials from being seen would work unless the player’s camera made it inside.
You could also look into fluid sim if you wanted this effect outside of a game environment in a smaller controlled setting, as it’s not feasible at scale.
So first things first, we’ll focus on your collision issue and I’ll look around a bit to see if I can find a good way to fake the bowl not filling. I love tech art/VFX but it’s not my strong-suit!