Borderlands 4 never misses an opportunity to mix humor with adventure, and the Flat Kairoser side quest is a perfect example of that formula in action. This mission cleverly parodies "flat world" conspiracy theories - except it's about the icy planet Kairos, and one particularly stubborn believer named Skeptical Sam. Players will have to follow Sam across the snowy tundra, debunk his beliefs with scientific proof, and survive plenty of chaotic firefights along the way.

This walkthrough covers everything you need to complete the Flat Kairoser mission in Borderlands 4, including quest details, all objectives, and how to efficiently finish each step while grabbing rewards along the way.

Flat Kairoser Quest Overview

·Quest Giver: Skeptical Sam

·Location: Southern Terminus Range

·Prerequisites: Complete "A Lot to Process" main mission

·Rewards: XP, Cash, Random Weapon (Uncommon-Epic), Vault Hunter Customization, ECHO-4 Customization, and Eridium

You'll find Skeptical Sam south of the Grey Havenage Safehouse in the Terminus Range once this area becomes accessible. Speaking to him begins the quest, where he insists that Kairos is "as flat as a critter's pancake." Your job? Prove him wrong - scientifically, of course.

Flat Kairoser Mission Objectives

1. Take Flat Kairos

2. Stomp dang globe

3. Follow Sam

4. Reach Shrine

5. Reach the wrecked ship

6. Collect surveying equipment

7. Find a suitable launch site

8. Place atmospheric surveyors

9. Activate surveyors

10. Find the balloons

11. Talk to Sam

Step 1: Take the Flat Kairos and Stomp the Globe

After talking to Skeptical Sam, he hands you a model of "Flat Kairos." He then points out a globe on a nearby rooftop and demands that you "flatten that fake ball." Jump up to the roof and perform a slam attack (jump, then crouch mid-air) to crush the globe. Sam cheers you on, confident you've proven his theory correct - for now.

Step 2: Follow Sam to the Shrine

Sam wants to show you "evidence" that Kairos has no curvature. Follow him up a narrow mountain path marked on your map using the ECHO-4 scanner. Grapple points help you climb higher ledges while fending off Kratch swarms. At the top, Sam points to the horizon - insisting that "flat means fact."

The Vault Hunter, unimpressed, decides to find real evidence.

Step 3: Reach the Wreck of the Big Carl

The next location is the Wreck of the Big Carl, a massive derelict ship infested with Rippers and Warhorns. Eliminate all hostiles, then begin gathering Surveyor Parts scattered across the area.

·The first part is next to an outhouse behind the wreck.

·The second part sits atop a metal arch.

·The third part lies on the wreck's roof, accessible via the same grappling path used for the second part.

Once all three Surveyor Parts are collected, Sam suggests using them to "measure Kairos' flatness" - ironically setting you up to prove the opposite.

Step 4: Find the Launch Site

Follow the new waypoint to a high-altitude plateau using scalable walls and grapple points. Expect resistance from Creeps and other mobs on your way. Once you reach the ridge marked in your ECHO-4 map, you'll find an area large enough to set up the surveyors.

Step 5: Place and Activate the Atmospheric Surveyors

In a wide clearing with a giant bone structure, clear out all enemies. Then, interact with the glowing markers to place the three atmospheric surveyors. Once placed, approach each one and activate it to launch them into the air via balloon mechanisms.

This triggers the next objective - collecting the data these floating surveyors gather.

Step 6: Find the Balloons

Now, you'll have to retrieve the surveyors once they complete their readings. Each one is drifting across the snowy wilderness.

·First Balloon: Located at Shredded Summit. Use your Digirunner to reach the area quickly. After defeating enemies, shoot the balloon down to collect its data.

·Second Balloon: Head further west. You'll see it approaching, but it's destroyed mid-air by enemy fire.

·Third Balloon: Thankfully still intact, this one drifts near a shack with a tall antenna. Grapple to the roof when prompted, grab the balloon, and recover the last photo set.

With all three photo data sets secured, it's time to return to Sam.

Step 7: Talk to Sam and Upload the Photos

Travel to the Gilded Drop area and locate Skeptical Sam perched atop a tall tower. Climb up using the grapple points and speak to him. He asks you to upload the surveyor photos to a nearby terminal.

·Upload the first photo (shows nothing special).

·Upload the second (shows clouds).

·Upload the third, which clearly depicts Kairos' spherical shape.

Even with proof in front of him, Sam refuses to believe it. He declares he'll "see the edge himself" and climbs aboard a makeshift hot-air balloon. Unfortunately, his flight ends almost immediately as he collides with a mountain and falls to his death - a darkly comedic end to his "research."

Flat Kairoser Quest Rewards

After completing the upload, the mission ends. You'll receive:

·XP and Cash

·Random Weapon (Uncommon to Epic)

·Vault Hunter and ECHO-4 Customizations

·Flat as a Fritter Cosmetic Skin

·Bonus Eridium

Final Thoughts

The Flat Kairoser side mission is one of Borderlands 4's most memorable comedic quests, packed with satire, exploration, and a touch of tragic irony. It's a great showcase of the game's humor and an excellent opportunity to grab extra loot, XP, and cosmetics while exploring Kairos' frozen frontier.

If you're farming Borderlands 4 Items or looking to buy Borderlands 4 Money to power up your Vault Hunter faster, completing missions like Flat Kairoser adds a fun, lore-rich way to enhance your overall progression - all while proving that Kairos is, indeed, not flat.