It's a NO-NO to go late to a resort during summer weekends in Subic, as walk-in guests, particularly on a Saturday.  It seems everyone is heading to the beach during that time.  Everyone wanted to beat the intense heat!
Inside Subic, there are only four beach resorts - Camayan, Adventure, Sands of Triboa and All Hands.  For day tours, advanced reservations for the cottages are not allowed.  They all observe the "first come first serve policy".  
 
