I'm not an all-day music festival kind of guy and I don't know what the rules are like. So if any of my suggestions break those rules, my apologies in advance.
This list looks a lot like what I bring to all-day outdoor range events, minus of course the firearms and related gear.
- Food and appropriate beverages
- Picnic blanket and/or camp chairs if appropriate
- Appropriate clothing for the weather, to include at least one extra layer and rain/wind protection, at a minimum
- Sunscreen and bug spray
- Maybe a beach umbrella or canopy for sun protection
- A way to charge my phone
- Trauma and boo-boo kits
- Some way to clean myself up, such as a fresh pack of baby wipes
- A way to pack out all of my trash
- A multitool
- An extra flashlight
- Ritter PSP
- Heatsheets 2 person emergency blanket
- Quite possibly a garden cart or similar for all that stuff