If your interest is reducing form factor then you should look in to mechanical counterpressure suits. As the name implies, these apply mechanical pressure to the human body to prevent expansion.
One such suit is the MIT Bio-Suit, which may be used for the Mars mission.
MIT Bio Suit next to the Mars Mark III planetary hard suit.
There has been active research into EVA suits where the body is protected from vacuum just from the suit itself being very tight, rather than being inflated with a fluid such as air or water. They are generally known as Mechanical Counterpressure Suits (MCS), or Space Activity Suits due to the promise of increased mobility.
Such suits are very promising. ...
Wouldn't that be a bit impractical as the astronaut would be swimming in water. Unless I'm missing something, also their fingers and toes would look like raisins after the space walk. Getting in and out of it would be a mess too, with the water escaping and getting everywhere.
Another consideration is that air is breathable and contains oxygen which is somewhat useful for respiration.
Having a suit filled with air will provide a small reserve of air in case the life support systems have problems.
Also, getting in and out will be a lot messier if the astronaut has to get into a "bath" rather than into a suit.
There's no advantage to replacing the air with water.
you're adding weight.
you're adding resistance: when you move around, water will flow around the body and because you're proposing a thin layer of water, the flow is obstructed which means it takes energy to push the water around.
you're replacing the air layer (which is a reasonably good thermal ...
...a thin layer of water that was held down by oxygen up at the head.
"Held down" doesn't work so well in weightlessness. Water would move around inside the suit, climb up the astronaut's neck and put them in danger.
This happened to ESA astronaut Luca Parmitano when doing a space walk at the ISS. See Space.com's Italian Astronaut Recounts Near-Drowning ...
The problem is how you would keep the water at the bottom and the oxygen at the top. In gravity environments such as Earth or Mars, the water would understandably tend to gather at the bottom and the oxygen at the top, due to buoyancy. This is fine, of course, and what you would expect. But what else would happen?
Your astronaut in such a suit can't even ...
These are two microphones of the cosmonaut's headset (шлемофон - hat with headphones and microphones). Two microphones reserve each other.
The ДЭМШ-microphone possessed considerable resistance to noise interference and selectivity to voice. For many decades, the ДЭМШ-microphone was installed in almost all Soviet military and professional civilian radio ...