Whatever your choice of container, don't bring something gigantic. What To Wear Assuming the weather is toasty warm, shorts or swim trunks and a tee-shirt are the obvious choice. If you wear long pants I would suggest sweat pants. You will need to pull the legs up when getting in and out of the raft. You may want to bring some extra clothes along in case the weather turns cool or in case you get drenched.
Beginners tend to be the wettest of the bunch.
Extra clothes can be sealed in a plastic bag or a dry bag. Sandals or filp-flops are o.k., but little pebbles tend to get between your feet and the footwear whenever you get out of the raft. Not the most comfortable feeling. I would suggest a closed water shoe. A low cost pair can be found at a local department store.