I searched the forum and with my search results I found no topics containing this info, It seems if you place equipment underwater it can't be shot! I don't know if they can be blown up but for example on Karachi in the building with the ladder and broken building beside it there is a small pool of water as you enter on the ground floor, throwing C4 into the pool and shooting it will have no effect on the C4 but you can still detonate it but seeing as there are not to many maps with ankle high and plus water its not much use, but still its worth pointing out if you want bulletproof equipment. PS: Its good for headquarters most people will camp in the pool!