Throughout Zanzibar Land, numerous hidden rations and ammunition caches are tucked away in obscure locations. These are not always in plain sight and often require thorough exploration. Check behind crates, under desks, inside lockers, and even in ventilation shafts that might seem like dead ends. Some areas might have destructible walls that reveal secret rooms containing valuable supplies. While not a 'quest,' actively searching for these resources is highly recommended, especially on higher difficulties. Having a healthy stock of rations can be the difference between success and failure in a tough boss fight, and extra ammunition ensures you're never caught unprepared. Always revisit areas if you acquire a new item that might open up previously inaccessible spots.
While Metal Gear 2: Solid Snake relies on manual exploration of interiors, Metal Gear Solid V: The Phantom Pain evolves this scavenging by using the binoculars to tag distant supply crates.