I just want to add a general comment to this old thread. A lot of people have recommended various devices claimed to be waterproof. Before you buy one of those, I suggest that you first look into exactly what “waterproof” means. For the purpose of a key fob it would mean “impervious to water when submerged.” But how deep, and for how long? This is defined by IP (ingress protection) codes issued by the International Electrotechnical Commission). For example, a device rated IPX8 can be submerged at 3 meters or more for at least 30 minutes. IPX7 protects up to 3 meters. IPX4 protects only from splashing water. Helpful chart: https://craftcadence.com/blogs/backpacks/ipx-waterproof-guide
So the questions are: Is a waterproof case rated? Do users report that the device actually works as promised?
To start with the popular Pelican boxes, they are rated as IP67––waterproof in up to 1 meter of water. That’s not all that impressive. If you drop the case in 1 meter of water you can hop out of your kayak and retrieve it by hand. What about deeper water? Many reviewers report that Pelican cases failed to protect their contents when submerged.
What about drybags that you fold several times to seal? The Backsak by Skogokust ($70) is IPX6, which is not a submersible rating––not much bang for your buck. This beefier drybag by Grizzly Peak has IP66 printed on it––again not submersible. https://www.amazon.com/Grizzly-Peak-Waterproof-Lightweight-Adjustable/dp/B07DM9YCR3
This drybag backpack is rated IP68––submersible to 1.5 m for 30 minutes.
More claimed ratings: Aquapac IPX8. Dripac IPX8. NiteIze IPX7.
Reviewers report failures for most of these cases and bags, especially with cellphones, cameras, and keyfobs. This can also indicate user error––some of the devices are difficult to close perfectly. And it can happen that a device is generally good but a specific one has a defective seal, hence the advice to test it by placing a kleenex in it and submersing it.
A final question is whether the protective device floats. Some cellphone cases have an air bladder and a drybag may float if it has air in it. Some cases, like my Nite Ize, are going straight to the bottom.
My point is that if you have valuables like a camera, you shouldn’t assume that something like a Pelican case is going to protect it just because it’s widely available and a well-known name. Check the IP rating and read the reviews carefully. Also consider a double or triple layer of protection, like a Pelican case inside a drybag in a hatch. Keeping your keyfob in a waterproof case in the pocket of your PFD is a way to overcome the problem of submersion over 3 feet. Although the Nite Ize is only IPX7 (1 meter, 30 minutes) I’m comfortable with that because it’s in my PFD pocket, but I’ll keep my eye out for a better IPX8 case.