Far Cry 3's Rook Island has many beaches, but the one in question is the one where Jason, Riley, Daisy, Grant, Liza and Oliver share Sambuca shots in celebration of Riley having just gotten his pilot's license.
This beach is significant for more than just that, though.
After skydiving without anyone on the ground to meet them, the gang lands on the beach and finds it infested with pirates. They are quickly kidnapped and caged, with the intention being to ransom them to their rich parents before eventually selling them into slavery after getting the money. Vaas meets them and separates them all.
Jason must then systematically find and rescue all of his friends, setting the entire game into motion.