The third colossus in Shadow of the Colossus, known to fans as Gaius, or the Knight, is a little further away from the central point of the Shrine of Worship, and is also your first real challenge.
It's a whopping great thing, wielding a large "sword" made of stone, and the battle takes place in a restricted, arena-like area, too. That said, there is a knack to taking the Knight down, which we'll dive into in our guide on how to defeat Gaius, the Knight and the third colossus' location.
Cycle back to our main Shadow of the Colossus walkthrough, guide and tips hub for much more, meanwhile. Otherwise let's dive in just below.
Third colossus location and how to find Gaius, the Knight
The Knight, or Gaius or the third colossus, whatever you prefer, is located in similar direction to the second colossus that you just defeated.
Head north-west of the Shrine, doubling back on yourself as you walk down its front steps, and cross the natural bridge again, only this time take the left fork at the end instead of the right.
Continue on, angling slightly to your left after crossing the bridge, towards a gap in the rocks ahead that leads into a narrow passageway.
Out the other side of that will be bleak looking lake, with a large circular platform in the centre. A cutscene will trigger, and suggest to you that the spiralling ramp, emerging out of the lake, is the way forwards.
Swim over to the base of the ramp, head up it on foot, and jump onto (and grab!) the ledge of the suspended bit of rock at the top. From there, you need to shimmy round the right hand side of it, Uncharted-style, and then lean towards the circular platform's edge. Take a leap of faith, remembering to hold R2 to grab as you're in the air, and then pull yourself up onto the platform.
Grab onto one of the stone columns and climb up that onto the main platform itself, and another cutscene will trigger as the third colossus awakens.
How to defeat the third colossus Gaius, the Knight
The Knight wields a huge stone sword, and is the largest of the three colossi you'll face so far by some way. It has two weak spots, the first of which is right on top of its head, so you have some climbing to do.
Easier said than done though. To climb onto Gaius you'll need to wait for it to smash its sword into the ground, then run up it like a ramp, grapple onto its fur at the handle, and work your way up its arm - but the problem is, the third colossus has a guard around the sword's handle that stops you climbing any further.
You have two options for getting past it, one quite a bit easier than the other. The easy, and more deliberate way, is to lead the Knight to a position where it will smash its sword into the ground over the very centre of the big circular platform. There's a solid, metallic disc there (pictured above, that Wander is standing on) which, when hit by the sword, will cause the fragile guard to shatter.
Alternatively, for added style points (and a PlayStation Trophy…) you can try to jump over the guard, by standing on the Knight's sword and waiting for it to fling you up in the air. There's a knack to it, but really it requires more luck than anything.
Once you're past the wrist guard, work your way up Gaius' arm, onto its shoulder and back. There are points for you to recover stamina along the way, and if you fall try to time a roll (with Circle) as you land. We can't completely confirm it but it does feel as though it mitigates some of the falling damage. Remember to try and grip onto the edge of the sword if it tries to shake you off as you climb back up, too.
For more explainers, tips and detailed advice on Shadow of the Colossus' PS4 remake, our Shadow of the Colossus walkthrough and guide can help you hunt down and kill every colossus, including the tricky third Colossus, eighth Colossus, ninth Colossus and eleventh Colossus. We also have explainers on all Agro tricks, how to find and use lizards and fruit and Enlightenments, and where to find a The Last Guardian Easter egg and all Shrine locations.
When you get to the colossus' head, give it the usual handful of angsty stabs, and then prepare to work your way back down. The second and final sigil is on its stomach, in the centre.
We got there by climbing up the inside of its sword arm to the top half of it, then dropping down when it was above or close to the Knight's stomach platform - make sure to hold R2 as you fall if you do it this way! It's not the easiest thing to replicate, but was the best method we could find.
From there, it's a few more stabs to the belly button, and Gaius will fall, along with the third idol back at the Shrine of Worship where you're teleported to once again.