What is the name of Boeing’s maritime patrol aircraft based on the 737-800ERX?

Boeing’s maritime patrol aircraft based on the 737-800ERX is the P-8 Poseidon.

The P-8 Poseidon was developed for the United States Navy to replace the Lockheed P-3 Orion. Although it uses the 737-800 airliner as its basic platform, the military aircraft has specialized systems, structural changes, weapons capability, and equipment for anti-submarine warfare, maritime surveillance, and reconnaissance.

The aircraft can carry sonobuoys and other mission equipment, and it can employ torpedoes and anti-ship weapons. Its sensors allow crews to search large ocean areas and track surface or submerged threats.

The P-8 is often confused with Boeing’s E-7 Wedgetail, which is an airborne early-warning aircraft based on the 737-700. The KC-46 Pegasus is also a Boeing 767-based tanker, not a maritime patrol aircraft.