From the Background: "According to the Marine Corps: The Amphibious Combat Vehicle (ACV) is the Corps' next-generation vehicle designed to move Marines from ship to shore [...]. Designed to replace the Corps' aging Amphibious Assault Vehicle (AAV - in service since 1972), the ACV will be the primary means of tactical mobility for the Marine infantry battalion at sea and ashore [...]. The ACV will possess ground mobility and speed similar to the M1A1 tank during sustained operations ashore and have the capability to provide organic, direct fire support to dismounted infantry in the attack. The ACV will support expeditionary mobility capability and capacity with balanced levels of performance, protection and payload. There are currently four ACV variants planned: (1) a Personnel Variant, which can carry three crew members with 13 Marines and two days of combat equipment and supplies; (2) a Command and Control Variant; (3) a Recovery Variant; and (4) a 30-mm Gun Variant. The Marines intend for the ACV to provide effective land and tactical water mobility (ship-to-shore and shore-to-shore), precise supporting fires, and high levels of force protection intended to protect against blasts, fragmentation, and kinetic energy threats."
CRS In Focus, IF11755
Congressional Research Service: https://crsreports.congress.gov/