I just spent a good portion of the morning watching this episode of National Geographic that's all about the very impressive Marine One helicopter. Like Air Force One, the Marine One moniker is applied not to a single specific aircraft but rather a whole fleet of aircraft/helicopters that support the transportation of the President of the United States.
There are 2 aircraft, specifically the HMX-1 "Nighthawk", that fly the President inside the United States and each of these helicopters are supported by a plethora of crew, pilots, and special forces that all work together to make sure the President is safe. I'm always so fascinated by these Presidential transport vehicles (like the limo, Air Force One, etc.) because they seem to have a somewhat dated appearance (or normal appearance) on the outside but are actually chock-full of secret tech on the inside. Like a sleeper car I guess.