TF171 was on a mission in the middle of the Atlantic Ocean, where there are several legends of serials, pirates, sea monsters, etc... But it's obvious that they didn't believe in any of these legends...

In the middle of the mission they ended up finding a large ship, which they thought was abandoned...

So they just got on the ship, and were exploring..

Soap: "Captain, I think this is just an abandoned ship.."

Price: "Okay Soap, I think so too. Guys, let's go back!"

Price speaks but when everyone turns... There you are with a deadly look pointing a VERY sharp sword at the Captain's face.