One of the first custom moves for my first AW game read pretty much exactly like your tunnel crawling move. That... worked like the first time or so it was used, but after that it was just a problem. It kept getting in the way of a story, especially if the story required a dip into "the tunnels" but that dip was not really important to the momentum at the time. Long story short, I found I had drastically overcomplicated things.
Acting under fire is a much better choice in this regard, because you can tell them if they're in the tunnel long enough, or deep enough, to trigger/not trigger the move. And even then? It's not needed. Consider this:
For the random "event" that this move introduced, again that could actually cause you problems. If someone is using the tunnels to join back up with the group to finish up some cool thing, and then they get hijnked into some event they didn't want to do, they others might have to sit there and wait through it. Not always a good thing. Consider instead, that you announce that the tunnels are dangerous, and if they decide to use those tunnels... then you now are presented with an opportunity for fuckery if you think an event here would fit nicely with the tempo. You can always give them the opportunity to avoid the same as before too, by announcing the badness and letting them try to get through anyway.
Joe: "I'm heading through the tunnels into the building behind that place. I want to get a good vantage for when the rest of our group heads right up to the door. I'll signal them when I'm there."
Rest of the Group: "We're heading in as soon as we get Joe's signal"
You: "Alright roll to use the tunnels."
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At this point, everyone is waiting for him to do this thing. The excitement is about to occur. The tunnel foray provokes a move, which if he uses the tunnels often, he's had to roll all the time. If he hits a 7-9, he either has to deal with a horrible uncertain miss of the maelstrom... on a partial hit? he can make everyone wait a long time for him. "safe but boring?, costly but boring? boring." Or he can run into trouble, which could take a whole lot of game time to resolve and that also means everyone else is waiting for him, since trouble is assumed to not take as much time as the option that it takes a long time. Meaning you're also hamstringing yourself here, because the trouble cannot slow him down cause he didnt choose that option AND he got a partial hit.
This doesn't sound like a good set of choices.
Let's instead consider something like this, rather then a move:
"The tunnels are dangerous, some people talk of weird smells that fuck with what you see and how to think. Others just go in and get lost, sometimes they just lose their way in their thoughts... starving to death just feet away from an exit. And that's when the tunnels are empty... now, the tunnels are not always empty my friend. No. Sometimes horrors unimaginable dwell there"
A nice bit of thematic text. You give yourself this the following quick bit of advice:
• Always barf forth some apolocalyptica to unnerve them or worse if they go into the tunnels
ex: Joe goes into the tunnels to get up and behind the location. "You grab the rungs leading down and slide in to the darkness, hitting the tunnels floor with a soft splash. You know it's only a short distance, but you have to look back up to remember what direction your facing. You get a shiver run through you. What do you do?" bla bla bla he makes he way deep into the tunnel. "When you're reaching the other end, you hear something and pause. A ripple brushes against your heels and something shifts in the darkness out of the corner of your eye. What do you do?"
You just always fuck with them in the tunnels, it doesn't even need to be real. Joe could shine his flash light all over the tunnels and it'll be empty, the floor rippling with his steps... or something else's. It's just to unnerves them. Then he climbs back up and the rest of the action happens as needed.
If someone is willing to spend a long time in those tunnels getting to a place... They're just asking to be fucked with. Decide, toss the flavor at them and if they seem to be interested, or if nothing else is going on, or if they're being sloppy / in a rush about things... make things different. Maybe they actually see/hear/smell something, maybe it chills them to the bone. Maybe they know if they dont move, they might be in a life or death fight against something they really dont want to fight. They can try to get away with an act under fire. If they hit a 7-9, then maybe it takes awhile, maybe they drop something, maybe they saw something that'll haunt them. Who knows? Creativity is bountiful.
Maybe if they get lost in the gasses in those tunnels, the ones that fuck directly with their brains, maybe they need to open their mind to get through the stuff. Maybe that's the only way. It'll be interesting, no matter what happens. Maybe they'll even try to bottle and use the stuff in an interesting way later, who knows. Play and find out.
Random events, tracking resources, these aren't typically AW's domain. Thematic terror? emotional or psychological shit? Yeah, that'll all good. Human needs, wants, fears, sins, darkness, and all the brighter stuff too. This game is about the people, not really the things. The things are stuff they either have or don't have, the moves are about the people and the effects those things (lack or surplus) have on them.
As a quick final note... Be wary of any moves that would effect a groups travel that might have to either ll be rolled separately or always handled by one person. What if a group goes in, most with a bad stat for the tunnels, but they go in with that one guys that knows them. Can he roll with their aid? What happens if they run into something and get seperated? The roll was a success, so they all get to the location, but now they've got some weirdness, do they have to roll again, for each seperated member now? They already had the group roll... so you gotta be careful not to nullify the success.