Visit, board, search, and seizure (VBSS) is the term used by United States military and law enforcement agencies for maritime boarding actions and tactics. VBSS teams are designed to capture enemy vessels, combat terrorism, piracy, and smuggling, and to conduct customs, safety and other inspections.

Naval boarding action is an offensive tactic used in naval warfare to come up against an enemy watercraft and attack by inserting combatants aboard that vessel. The goal of boarding is to invade and overrun the enemy personnel on board in order to capture, sabotage, or destroy the enemy vessel. While boarding attacks were originally carried out by ordinary sailors who are proficient in hand-to-hand combat, larger warships often deploy specially trained and equipped regular troops such as marines and special forces as boarders. Boarding and close-quarters combat had been a primary means to conclude a naval battle since antiquity, until the early modern period when heavy naval artillery gained tactical primacy at sea.