We each carry cell phone, 3 bottles of water, a couple of zip fizz, a compact umbrella (from the $ store) an extra shirt , sunglasses and lip balm everyday to the parks.
I carry in addition to the above: camera, wet wipes,Hand sanitizer, a small first aid kit with bandaids, blister block, tylenol , sunblock, a hand towel from the hotel and copies of our ADRs.
DS and I have Bagallini messenger bags and dh has a daypack.
Everything is easily accessible and protected from water.