You have to wear either shoes or sandals when you get on the raft. They won't let you on barefoot.
You're wearing life jackets anyway, so why not make the most of them? Body rafting is a popular element when floating in the quieter Jordan River.
Yes, you'll be surrounded by water. No, that doesn't mean you won't need to bring your own along.
You're getting more sun exposure on the water, so do wear sunscreen. And plenty of it.
Again, you're going to be in the sun at least for some parts of the trip on the water.
While this isn't a whitewater rafting trip, you will get splashed and slightly wet. Which may be fun for most of us on a hot day but not so much fun for our phones.
Just because this is a relaxed floating trip doesn't mean there are no safety rules. Listen to the guide giving the talk at the beginning of your trip and follow the instructions.