Zac Efron [1] spent part of his Memorial Day weekend hiking in Oahu, HI, and he had a few special guests along for the ride. In addition to Instagramming an epic salute to the troops [2] and a glimpse at Workaholics star Adam DeVine [3], Zac was also spotted hitting the trails with none other than Anna Kendrick [4]. Zac, Adam, and Anna are all set to star in the upcoming comedy Mike and Dave Need Wedding Dates [5], which explains why the three are spending time together. Prior to his stint in Hawaii, Zac was filming Dirty Grandpa in Georgia with Robert De Niro [6], where Zac fit in a little quality time with girlfriend Sami Miró [7]. Keep reading for the pictures from Zac's hiking day.