Below are some locations of chests in the game that are not marked on the map such as “Guarded Treasure” or “Smuggler’s Cache/Sunken Treasure”. These chests can have *potentially* good loot contents. I’ve gotten some diagrams and some recipes from some of the chests. Sometimes just armor or gear and then some crafting materials. You may not come across some of these locations while playing the game and missed out on them so here they are.
Note that chest contents can be random. So chest containing not so good contents for me, might contain something valuable for you or vice versa.
1) This one is near the quest area of “Queen Zuleyka’s Treasure”. It’s not the treasure itself, but if you look just north of the quest area, there is another chest beside a ship. I got a “Maugrim” relic sword on this chest.
2) This one is near the Harpy Grounds. Just below that hill there is a house rubble with a chest. Got a “Mag Deira Cuirass” diagram here.
3) Was pretty high level when I discovered this place, so had a lot of diagrams already unlocked. But i included it here since you might get something else when opening the chest at a lower level.
4) Above the the Widow’s Grotto marker, you’ll find a guard tower. Somewhere below the tower is a chest hidden in the bushes.
5) This one you might come across since there’s a very small event here. Just near the Boatmaker’s hut. The chest is located beside the bridge. Got enhanced saddle on the chest, early gear for Roach.
6) Nothing extraordinary for me on this chest. But since its random, you yourself might get something good. This chest is located underwater, just east of Fykes Isle. South of the Drudge marker.
7) This one is near the bandit’s camp marker. In the lake, underwater, there is a chest. Got a diagram for Bremervoord blade.
8) You can’t access this one anytime, but during the “A Matter of Life and Death” quest, you’ll be able to enter this estate. During the last part, you’ll be in a “hedge maze”. In that maze, there is a chest. I got greater Glyph of Aard there.
9) I got the Archgriffin Decoction on this chest (and a Sapper’s Diagram). The chest is on a watch tower in the swampy area north east of the Nilfguardian camp.
10) This one is South Velen. West of the the Frischlow marker, just beside the dirt road is a dead body. Got Knight’s gauntlets diagram and horse blinders here.
11) This one is on the wrecked ship. You have to swim a bit for these. There are 2 chests on the ship. I only got some horse gear here. You might get some other loot though.
12) Just some enhanced saddle beside the road near the Duen Hen marker.
13) Underwater, near the Southern gate marker. Got Gemmerian Steel Sword diagram.
14) This one is located on an attic in one of the houses outside Novigrad. Just find the stairs and in the attic, there are 2 chests. You might get some recipes here or a relic sword, but in the pic below, I got a diagram for Spikeroog aketon and Hunter’s boots.
15) This one is on a big warehouse in Novigrad Docks. I got the recipe for Moon Dust here.
16) This one is also located in Novigrad Docks. It is on the last ship on the docks as shown in the map. Got manuscript here for Superior Beast Oil.
17) This chest is where I got the Superior Hang Man’s Venom manuscript. It’s on a cliff as shown in the map on northern corner of Novigrad.
18) This is on Oxenfurt, under the South Bridge. You’ll find 2 chests. On the pic below you’ll see Superior Dragon’s Dream manuscript and Tracker’s gauntlets diagram.
19) This one is under the West bridge of Oxenfurt. Got Petri’s Philter manuscript and Mastercrafted silver sword Diagram.
19) Under St. Gregory’s Bridge. You’ll find two chests underwater.
Again chest contents can be random. So you might get the same stuff or some better stuff.