Wow
Got one of these recently. Pros: Gets very loud, very easily. Filled it with water and then tried it and yes, it works while submerged! Feels tough considering it's plastic. Cons: It's reasonably large so it's one for a BCD or lifejacket rather than EDC. Overall: Really glad I got it, it's a whistle that's tough and loud that works when full of water, what more can be said?