Boundless Bay: Proving Grounds 11 (Bastion Guide)

The blue water around Boundless Bay in Bastion

Boundless Bay is the proving grounds for the Galleon Mortar. It’s one of the few “chill” challenges in the sense that you’re not pressured by time.

Instead, you’re given 5 shots to blast as many Squirts as you can.

Your rank will be based on the number you’ve killed after using all 5 shots.

Boundless Bay
Rank Requirement Reward
1st All 90 Squirts “Bomb Barrage” Secret Skill
2nd 60 Squirts or more “Something Heavy” Upgrade Material
3rd First clear “Something Burnt” Upgrade Material


Invest in a Bigger Blast / Bastion
Invest in a Bigger Blast

You can make this test easier by improving your Mortar’s area of effect.

At tiers 1 and 3, choose the upgrades that give you the +25% blast radius. With those, you can hit a third of the targets even with one mortar strike.

You may also want the aiming speed upgrade at tier 2. It makes it easier to time your shots with some of the moving targets.

Galleon Mortar Upgrades
Tier Upgrade Name Effect
1 Burstone Bombs +25% Blast radius
2 Target System +50% Aiming speed
3 Shrapnel Charges +25% Blast radius

Strategy + Tips

The Slinger-Style or the Mason-Style / Bastion
Choose either the Slinger-Style or the Mason-Style

Tip #1: Use a mouse instead of a controller

Boundless Bay is the rare exception where a mouse is preferable over a gamepad.

A gamepad comes with an auto-aim function, which always makes your aim stick to the nearest Squirt. This works against you, because you need to target the floor and not the enemies themselves.

If you’ve been using a controller, you should switch to one of the mouse-based styles in the options.

Tip #2: Take your time visualizing where to launch a Mortar strike

Once you start aiming, you can’t exit out of it until you launch your attack.

The test also has no time limit, but you are limited to five attacks.

No time limit in Boundless Bay / Bastion
There’s no time limit

With these things in mind, take your time planning your shots.

Tip #3: Wait for the Squirts to move close together before firing

Most of the Squirts won’t wander away from their original position. The exceptions to this are the ones at the sides.

Aim at Where the Groups Merge (Animation)
Aim at where the groups merge

Every two seconds, they’ll move to the other end of the field. As they do, they’ll pass through the Squirts that are stationary.

That’s the best time to fire your weapon.

You can take down a lot of them with one shot by aiming at where the traffic merges. Using this tactic, you’ll only need 2–3 shots to kill the bulk of the targets.


All Prizes after Blasting 90 Squirts / Bastion
All Prizes after Blasting 90 Squirts

The challenge ends after dispensing your last shot or killing all Squirts.

  • You’ll get a Something Burnt for your Mortar regardless of your kill count.
  • If you’ve destroyed at least 60 squirts, you’ll also get a Something Heavy for the Cael Hammer.
  • Destroying all Squirts lets you unlock the “Bomb Barrage” Secret Skill for the Galleon Mortar.
Secret Skill: Bomb Barrage (Galleon Mortar) / Bastion

Secret Skill: Bomb Barrage
(Galleon Mortar)

When you fire the Mortar, you’ll unleash five orbs instead of one. These will devastate the area around your targeted spot. You can spread these out by aiming longer and farther.

At the Mortar’s max range, the orbs will fall along a line perpendicular to you.

Louie Nelson Zafico

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As a frustrated otter who dreams of getting published, Louie instead wastes his life cuddling his cats. He spent his childhood playing Suikoden, grew up with Total War, and matured (somewhat) with EU4. He hopes to someday find a geopolitical JRPG with the 4X systems of a Paradox game.

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