The seventh colossus in Shadow of the Colossus is known to fans as Hydrus, or the Eel Colossus.
It's the first underwater colossus you'll face, and is also capable of damaging you with electricity, rather than regular impact-based attacks, which makes it a particularly unusual foe.
Here, we'll explain the seventh colossus' location as well as how to defeat Hydrus, the Eel Colossus once you've found it.
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.
Seventh colossus location and how to find Hydrus, the Eel Colossus
The Eel Colossus is located right at the top - or north - of the map and a little to the west.
Head out from the Shrine of Worship, double back on yourself and cross the natural bridge to the north, as you have done a few times already for colossi two and three.
This time, continue on due north into the desert-like area, keeping the rocky cliffs on your left hand side.
They'll begin to curve to the left, so do the same so that you're now heading just about due west along the top end of the map.
Straight ahead you'll soon find some greenish ruins and a path through them over a lake. Hop off Agro and proceed onto the causeway, and a cutscene will trigger.
Continue on across that suspended path over the lake and hop over to the spiralling ramp. Work your way down to the bottom and as you begin to wade into the water, the second cutscene will trigger and Hydrus, the seventh colossus will appear.
How to defeat the seventh colossus Hydrus, the Eel Colossus
The Eel Colossus is probably one of the most unusual battles you'll have faced so far, forcing you to time your attacks and movement with the giant sea snake's plunges underwater and surges of electricity.
First up, you need to bait Hydrus into attacking, which is done by splashing around a bit on the water's surface.
After a bit of time it'll swim towards you, and then surge up underneath you as it passes by. When it does, you need to avoid its three electrified spikes - getting hit by one, will deal heavy damage to you - and also try to grab onto its tail.
The very end of the seventh colossus' body is coated in fur, which can be grabbed as it passes by. It's a little tricky to get right, but basically you need to make sure you line up with the beasts' trajectory as it passes beneath you - but after the final electric fin has passed - and then just hold down R2 as it does.
If you got your angles right you'll now be clinging onto its body, and immediately dragged deep underwater. Hold on, because although your stamina gauge will drop pretty low, the Eel Colossus will eventually come up to the surface.
From there, you need to gradually work your way along its body towards the head. It'll dip back under water periodically, and likewise its electric fins, or spikes, will periodically surge and zap you if you get too close, 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 reach an electric spike you'll find a glowing blue patch of vulnerability just before it. Stab it once or twice and the fin will stop glowing and no longer pulse with electricity or damage you.
You can now proceed to the next one - rinse and repeat, and then after two fins are down, the Eel will dive deep underwater again, this time forcing you to let go before you drown.
You then need to bait it into another attack the same way as before, and work your way all the way along its body again to the final fin, and then the glowing sigil on the top of its head.
A final stab to that, and Hydrus, the seventh colossus, will fall. You'll soon be whisked back to the Shrine of Worship and the seventh idol will crumble, and then it's time to hunt down whatever beast is next.