@Lord_Gareth Whoops, wrong copy-paste on that link. This page.

Oh?

There are two ways to advance.

One requires cunning and skill in discovering the secret use of a thing you've already encountered.

The other requires... basically dumb luck in stumbling over a secret use of a thing you've already encountered.

Assuming we don't want to count on dumb luck, go back to Crater Island, with the boiler.

Is there any place on that island you can see that looks likes a place you'd like to go, but your way is blocked?

I'm trying to remember the explosion experiment...

Been too long since I read the books, I guess.

You mean the steam-valve thing in the middle of the lake, with a lever and four pipes coming off it?

That?

Have you been able to open the boiler?

Ah, okay. I didn't know you'd gotten that far.

I thought you were still trying to get into the boiler.

You mean this, then:

No worries about response time.

Okay. When you pull the lever, what happens?

Aight. You can mess around with that, it's useful for a future challenge. But it won't get you further ahead right now.

Is there anything else up on that higher level?

You mean the ladder down to the caldera?

Then... I know exactly what your stumbling block is, but I have no idea how to give you a hint without just telling you the answer. It's a silly-simple thing that took me an embarrassingly long time to figure out, too.

There's one thing I can say, I think.

There's a standard thing which is common to nearly every part of the game--a way the world acts, or rather, interacts--which is untrue somewhere in the part of Crater Island that you have access to.

It is subtle and almost literally invisible, nothing you'd normally notice at all.

When you have identified that thing, that difference, your path will be obvious.

Oh, and don't ever forget to treat Riven like a real place.

You're really really close to a major breakthrough.

No, that is not it. I'm sorry.

Heheh. No worries. Would you like me to give you a narrow area to look in?

You'll find it in the upper levels, but looking up from the beach might help you figure out what you're looking for.

It's not a puzzle. You're overthinking it.

@Emracool Yes. It's right in front of you.

....well, I lie. It's not right in front of you.

But it's obvious, and all you have to do is reach for it.

Here, try this. Make a list of everything on the upper level.

It shouldn't take long.

Then cross off everything on the list that you've experimented with.

Ah, sorry, not what I meant.

Go up to the upper level and make a list of everything in arm's reach as you explore it.

I know exactly where you are, and you haven't listed everything in arm's reach.

Go back in to the fan/pebbles/lever area and walk back out onto the balcony, slowly. Write down what you see.

While you do so, keep in mind where the outside upper-level walkway should be in relation to you.

Every other door in the game closes itself behind you.

And now, I'm off to a Riḍván party. ttfn

@Emracool Fun was had!