I got this one last year and it was perfect. Didn't have to worry about a camelback as I could fit 2 water bottles in the outside pockets and 2 inside the backpack, along with everything else I needed.

Outlander Packable Handy Lightweight Travel Hiking Backpack Daypack, Black https://www.amazon.com/dp/B0092ECRLA/ref=cm_sw_r_cp_api_M9R0ybWBV4P9R