I know, just from reading this board in the past, that lots of people will suggest a little plastic bag. I've been on rides like those before and honestly I just put my phone in my pocket and it's been ok.
Coming from a girl who has had a phone ruined in WDW due to water damage, I now put my phone and camera in a baggie when on a water ride. Or when I think it's about to rain for that matter!
Sometimes I'll forget to grab one from the room before we leave for the day (my mother always bring a box because she knows how crazy I get ) and I wrap my stuff up in my poncho when on a water ride.
I agree, SM is iffy. While I would PLAN on getting wet on Kali. However, they do have a place to put your stuff in the center of the ride at Kali, but it's not the driest. Best to use a zip lock baggie.
Well, I carry a purse around the parks. That alone protects the stuff in it. But if I'm on a really wet ride, I do bring a cheap poncho (2 for $1 at the dollar store). I may where the poncho or I might just lay it across my lap and over my purse. For Kali - which gets REALLY wet - I bring a plastic bag and put everything in it that I want to stay dry. Then I wear a poncho and put the plastic bag underneath my poncho.
Of course, it helps if you have people in your party that don't ride those rides and watch your stuff for you
I actually have everything in my mini messenger bag, and in that mini bag, I also have a big plastic bag that I'll put the messenger inside of and wrap the top over so it will stay nice and dry.
Ziploc baggie. I used to not use anything, but after my cellphone and digital camera were 'killed' on splash mountain in DL 3 years ago, I take no chances.