How do alchemical bombs work underwater?
The rules appear to be silent on the subject.
You’re flat-footed unless you have a swim Speed.
You gain resistance 5 to acid and fire.
You take a –2 circumstance penalty to melee slashing or bludgeoning attacks that pass through water.
Ranged attacks that deal bludgeoning or slashing damage automatically miss if the attacker or target is underwater, and piercing ranged attacks made by an underwater creature or against an underwater target have their range increments halved.
You can’t cast fire spells or use actions with the fire trait underwater.
At the GM’s discretion, some ground-based actions might not work underwater or while floating.
Here are some possible rulings I might use at my discretion:
1. The water interferes with and/or dilutes the chemicals to the point of being ineffective even if you do hit and the flask breaks. Basically, treat it like a bludgeoning ranged attack. Auto miss and no splash.
2. They can only be used to attack creatures within your reach and they don't splash. (Ever try to throw a baseball under water? Even a bullet is slowed to non lethal speeds in 3-8 feet) It's almost a melee attack, but you release just before impact so your hand doesn't get caught in the effect.
3. They take the halved range increment of piercing ranged weapons, but otherwise work as normal.
4. Water breathing creatures are also sickened 1 because they are breathing the water full of hazardous chemicals.
5. They work as though on land with no penalties or modifications.
6. Due to mentioning "exposure to air" in the description, alchemist's fire, bottled lighting, and frost vials do not work underwater. Tanglefoot bags explicitly do not work underwater.
7. Thunderstones do double damage, do splash damage, and deafen within 30 feet. Water conducts pressure waves (i.e. sonic damage) much better than air. Try googling "hydraulic abdominal concussion", unless you're the squeamish type.
The rules say I have the discretion to say that some things don't work, not that they work different. So, for PFS 2,4, and 7 are probably not defensible.
How would you rule?