I have a pretty long list that I give folks with the caveat that it is more than you need. My daughters use that list, plus they bring four bathing suits and combo shampoo/conditioner.

Some things to add to the discussion:
- Refillable water bottle
- Hat
- Chargers/batteries for electronics
- Non-Deet bug spray, we use picaridin
- Non sprayon sunscreen

I bring generic Bonine and electrolytes to share. Both are good for hangovers. DEET and sprayon sunscreen can stain fabrics and DEET melts plastics.

Cheers, RickG