So i've been thinking about this for a long time, as a bit of a response to the free subbing after goals. I'm also a fan of Ice hockey and they have sometimes hard to understand rules, their to many players on the ice is one of them as they do allow people to leave the subbing area before the other player has left. I have been previously pretty ademant that it should be ONLY after goals to keep it from getting confusing, especially like during the pause for an advantage puck. But that is based on the idea that 4 players had to be in the sub box when the play started. Would it be possible to improve the subbing as I describe below, now that it is primarily in-water side-subbing?

My thinking is that we could make it so a player may enter the playing area before the person subbing out has completely left the area as long as he is:
a) On the surface
b) swimming toward the sub-box
c) within some distance of the box 3m, 5m to be determined, maybe even different rules for when the play has stopped like 1/2 pool during an advantage puck.
If a player is subbing out from being submerged they would still need to break the surface before their sub leaves the subbing area, so essentially there are always four players out of the play and on the surface, it might be however that they are only heading to the box.

One thing I think this would do is help to rebalance the defensive ability on the side of the pool away from the sub-box. generally it should speed up the game tremendously, and if it were effective enough I might even become an advocate of 5 a side play versus the strong opponent of the silly idea as I am now.
I think concernes about more than one person leaving the box, or players in the sub area submerging to watch the game will be no different than they are currently. As far as making the call, it can be hard to see as it is, we've already hijacked threads other places to hear arguments about how to help the deck ref see sub fouls, all that would need to happen here is a slight delay in the call to make sure one of the surface swimmers actually leaves the playing area.

What do y'all think?