The fluid might increase the angle of view.
Vodka or Gin are probably best.
Absolut maybe.
Whisky, I have found gives a brownish cast
I mentioned the U.S. guy who sat at the bottom of his swimming pool and saw the Andromeda nebula more clearly as it got squashed lengthwise by the water refraction.
It would cost quite a bit to fill the pool with Vodka.
(I must admit to having knowledge of the subject, as the family were involved in the off licence business for a hundred years. But that closed over twenty years ago.
One of our bottlers fell into an enormous 3m high barrel of spirits and was just saved from drowning.
I did know how to bottle, label and place the corks in bottles as a youngster.
If you dropped a J. Walker bottle it broke, because of the square shape. Round bottles were stronger and usually bounced.
A champagne bottle cork went through our thick plate glass window on a very sunny day after the cork exploded off the top of the bottle.
Personally, I drank very little, seeing the effects it had on people.)