Through the course of Song of the Deep, we collected enough treasures and sub upgrades to beat Rimorosa without a struggle, but there are the rest of the 209 treasures and 49 upgrade items still to be found, scattered around the game world. All of these items appear on your map, but some of them require a bit of work. Here are the tips and tricks to help you along the way to 100 percent.
The most common method you'll use to find some of the harder to reach treasures and items is to just ping your sonar nearby.
If you find yourself in exactly the right position according to the map, but can't see anything there, ping your sonar to see if that reveals a chest.
These chests appear to not have a grapple point. Hit them with an ice shot, and the chest will float up and flip over for you.
Hit pufferfish with ice shots and magma bombs to manipulate their positions. Ice shots will float them up, and a magma bomb will make them sink.
If you find a stone head facing left or right blocking your way, you can often pull them out of your way like a gate. Hit them with a magma bomb to create a grapple point, and use your claw to pull it out of the way.
Some stone heads are facing forward. Ping your sonar near their ears, and they will open their mouths to release the treasure.
In your search for every item and treasure, you'll find a few chests wrapped in chains. You need to break them with something you can find nearby. Sometimes, this is a rock suspended precariously above the chest. Sometimes, it's a mine or Formori warhead. Keep your eyes open, and explore to find your tool.
Once you have the Full-Spectrum Search Light, you can use the high-powered beam to make any anemone hide, allowing you safe passage through anemone-lined hallways. If an anemone is protecting a chest or treasure, you can claim it once your light makes the anemone retreat.
Some treasures and items are trapped behind a silver plant. Look nearby for both a glow bulb and a school of fish. Lead the fish to the plant, and they'll devour it for you.
Metal walls, like the chained chests above, will always have an explosive nearby that you can use to destroy them. Don't waste your time trying out every upgrade, torpedo or trick you have. Again, keep your eyes open and explore.
If you find a group of snakes near where the map insists there's a treasure, try scaring them all at once.
If there is a treasure on the map that you just can't find, and there's a beam of light nearby, look for clumps of mushrooms on the walls and floor. Reflect the beam into the mushrooms in rapid succession to spawn the treasure.