Waterproofing technology.... Whatever you choose, it is not perfect. Nothing will survive immersion for hours, what you are doing is buying time, and in some cases, impact resistance.
You can go flexible, or you can go hard shell. Hardshell gives superior impact protection, and if the seals are good, great immersion protection..... A hard shell is the easiest to get gear in and out of but they are very hard to carry on a kayak. You can get a kayak deck bag.... And they are supposed to be waterproof, but they are not.... Roll the kayak and when you come up, it comes up with LOTS of water inside.
An interesting variation of hard shells are beta cases, a round lens case that provides great protection from impact and from immersion. They are the best way to carry a lens in a kayak.
Dry bags work well.... But beware of condensation and make sure you get at least 3 or 4 rolls of the top. Avoid the ultralight hiking bags because you will wear through them VERY fast. Avoid the clear ones because they are sticky and hard to get gear in and out of. I put a small towel and a desiccant pack into the dry bags to save me from minor leaks.
You can also go for a waterproof P/S camera.... But beware.... They do not float. You can get a float to hook onto the camera strap, or you can be like me and keep it in the pocket of the PFD and have a safety cord.
In the pictures.... Left to right... 10L dry bag that holds a DSLR and a good sized lens, 5L dry bag that is good for a compact DSLR and small lens (I use it for an SX-50), a pair of Beta Shells, and a Pelican case with a waterproof P/S on top of it. Behind is a LARGE pelican case and a guard animal to keep mice and tuna away from the gear. The bottom picture is a deck bag.... Use to hold your lunch.... Do NOT put a camera in it.