Lair of the Octoballs
Lair of the Octoballs is the second mission available in singleplayer Octo Valley.
Octo Valley
The kettle for this mission is along the walkway after the first kettle.
Walkthrough
Beginning
Travel down the ramp immediately in front of you, which leads to a small platform surrounded by crates and an Octopod. Kill the Octopod by shooting it with ink 
. Destroy the six surrounding crates for a couple of Power Eggs, then ink the wall just ahead and swim 
up it for a few more.
Checkpoint 1
You will encounter another open area, this time with six crates with four Octopods on top. They will immediately jump down and approach you, so splatter the Balloon Fish to take them all out easily.
The wall ahead of you will now be covered in ink, so swim up it and shoot ink at the next slightly curved wall you come across. Travel up this wall, and shoot the Octopod waiting at the top. Make a somewhat wide U-turn and coat the next ramped wall with ink, collecting Power Eggs as you make your way to the top. An Octopod will likely drop down as you are swimming up this wall, so be careful to avoid its explosion. Destroy the two small crates for some Power Eggs, and swim up the wall to your left after coating it in ink.
Upon reaching the next platform, you will be met with a ramp leading up to a large wall with a Balloon Fish and four Power Eggs. Simply shoot the Balloon Fish until it explodes, and swim up the wall. At the top of the wall, there will be a power line covered in Power Eggs. Collect these and activate the launchpad .
Checkpoint 2
Travel forward until you reach a grated ledge, overlooking a large area with crates and an Octoball perched atop a stack of them. Destroy the crates from the safety of the ledge, and splatter ink until the Octoball becomes submerged in it. Shoot the Octoball. Drop off the ledge, ink the ramped wall, and swim up it to reach a path littered with Power Eggs.
Collect the Power Eggs and turn left. Spray ink along the inclined pathway and slowly begin traveling up it. However, stay near the bottom, as three Octoballs will appear and begin rolling toward you. Wait until they become submerged in your ink, and get in a close enough range where you can shoot them. Swim up the incline, ink the next wall, and swim up it.
Checkpoint 3
Immediately turn left and collect the Power Eggs. You will encounter a large wall below a grated ledge. However, this wall is guarded by a Squee-G, an Octarian enemy that cleans up Agent 3's ink. Spray ink on one side of the Squee-G to distract it, then ink a path on the other side and quickly swim up it to the safety of the ledge.
After turning the corner, drop through the ledge by turning into a squid. You will land safely on a small outcropping with a crate and launchpad. Destroy the crate, collect the Sunken Scroll hidden inside, and then turn around and use the launchpad to return to the grated ledge.
Continue walking along the ledge, collecting Power Eggs, until you reach a grassy platform. Turn left, destroy the crates, and splatter ink on the ground to submerge the awaiting Octoball. Kill it once it is submerged, then turn left and ink a path up the next wall. This wall is partially covered by a window, so you must spray ink in an "L" shape and travel up it to the next platform.
Relevant Objects
In a wooden box beneath a floor grid on the 2nd checkpoint area you will find the Sunken Scroll of this level, and on a Squee-G that is in the area of the checkpoint 3 you will find an armor.
