 Beach measurements are often assigned to naval SR units like the United States Navy SEALs or UK Special Boat Service.Beach and shallow water reconnaissance, immediately before an amphibious landing is direct support to the invasion, not SR. SR would determine if a given beach is suitable for any landing, well before the operational decision to invade.There is a blurred line between SR and direct action in support of amphibious operations, when an outlying island is captured, with the primary goal of using it as a surveillance base and for support functions.