Cover while kneeling in water?

[Mighty264]

Carrion Crown is the 1st campaign I've ever run and I'm having some issues with combat in water. We’re up to book 2 called ‘Trial of the Beast’. There is a part at the end when you are fighting in a building that was partially flooded. The water comes up to 3 feet. Per the rules “Characters swimming, floating, or treading water on the surface, or wading in water at least chest deep, have improved cover (+8 bonus to AC, +4 bonus on Reflex saves) from opponents on land.”
1)The players decided to kneel down so that they would be chest deep to get the +8 bonus to AC, and use ranged attacks. Is this possible & if so are they considered to have firm footing on their knees?

While the players are walking in 3 feet of water they come to an area that drops to 25 feet of water.
2)The players decided to, once again, get on their knees. They put their heads under the water & shoot their bows so that they can get by the total cover the completely submerged creatures in the water have. Is this possible & if so are they considered to have firm footing on their knees?

[Grishnackh]

Part 1:

This one pretty much comes down to your opinion as a gamemaster and it all comes down to the kind of ranged attacks they are using. I havn't personally shot a bow or sling in my life, so i can't give you first hand experience on them. I would argue that shooting a crossbow is comparable to shooting a rifle so that part is more accurate.
So in case of crossbows i would definitely say that kneeling is even better then standing considering the "firm footing" part. I dont know how a bow or sling behaves in a kneeling position compared to standing. When in doubt i'd say a kneeling position is no problem rules-wise.

Now for the water part: I'd say (without any firsthand experience) that it should be possible to shoot a bow if the bow is partially submerged, but the arrow is not. Maybe give it the good old -2 circumstance penalty. As long as you're kneeling crossbows should be no problem at all. If your players try to circumvent the -2 penalty by raising their bows above a usual fireing position give them the penalty anyways for the awkwardness of their fireing position.

If the arrow is submerged in water you should definitely use the rules for using ranged weapons under water.

Additionally if the Bow isn't Magic it should become useless or get the broken condition a short while after the combat, because the bowstring got wet.

Part 2:
You cannot kneel in 25 foot deep water unless you are way more then 25 feet tall. There is no sure footing.
If the party has their heads under water and attacks enemys above the waterline, the enemys should have either concealment or even total concealment (depending on how clean the water is, waves and the distance). Additionally there is no way you can even try to fire a bow or crossbow effectively outside the water if your body is completely submerged, so you should definitely use the rules for fireing ranged weapons under water.

/edit
i think i misread the second part. I thought the players would get into the deep water, not the enemys ^^

In this case: Use the rules for fireing ranged weapons under water. sure footing is a bit tricky if you are completely submerged as you will have a floating effect. Maybe give characters wearing leather, hide or no armor a -2 penalty or let them make a swimcheck, while those in metal armor shouldn't have a problem. concealment gets down to cleanness of the water and distance

[krevon]

It would obscure your vision when you put your head under water. Also bow strings don't stay taught when wet.

[Eldmar]

Also composite bows are not made from a single piece of wood, but multiple strips of wood, held together by glue and lacquer. If a comp bow gets wet such as from being submerged then it will fall apart. They should be kept in a special water tight case like a scroll case but designed for the bow.