Story related trophy - Can not be missed.
This one will pop at the end of the Tanker mission. Once you take all the necessary photos of RAY, the mission end cutscene will occur, and...
*** Spoiler - click to reveal ***...you will see Ocelot betray the Russians, go into an uber badass mode totally gunning down his own soldiers, then detonating the SEMTEX he had the Russians plant around the Tanker causing panic and mayhem across the ship.
Questions, corrections and neg vote justifications below.