Dedicate your fourth day to exploring the historical sites in Vung Tau. Visit the White Palace, a former French colonial mansion that now serves as a museum showcasing the city's history. Next, head to the Long Son Big House, a well-preserved traditional Vietnamese house that offers insights into the local culture. Don't miss the opportunity to visit the Niet Ban Tinh Xa, a Buddhist temple known for its beautiful architecture and serene atmosphere. Wrap up the day with a sunset cruise along the coastline.