One Stupid Geocacher


Geocaching is a GPS-aided combination of hide the Easter egg and orienteering for internet nerds. I have logged >700 caches since 2005 and had lots of fun.

Borås Tidning now reports about a not terribly thoughtful geocacher. He had placed a cache in a space locked with a combination lock. Part of the puzzle was to figure out the combination. So far so good.


The locked space was a sealed 650-meter utility tunnel excavated through bedrock for a sewage line at a depth of up to 10 meters below ground surface. And the sewage tends to leak hydrogen sulfide, which makes the tunnel a potentially lethal place to be unless you’re carrying a scuba-diving tank. And before locking the hatch to the tunnel with his combination lock, this geocacher removed a conventional padlock whose key was held by Mark municipality.

Don’t try this at home, kids.

Update same evening: The kids who placed the cache have spoken to the newspaper, claiming that a) they found the hatch rusty and unlocked, and b) there was no sign suggesting that the tunnel was dangerous. Municipality staff do not challenge these statements, but contend that the kids should have understood that they were not allowed to enter the tunnel. As far as I can tell, there is no solid evidence for how dangerous the atmosphere in the tunnel really is.

Thanks to Niklas Krantz for the tip-off.


  1. #1 Victor
    June 22, 2011

    Wow, that is crazy. I’m a Geochacher myself, but shake my head at the extremity of some of their projects.

  2. #2 Martin R
    June 22, 2011

    Maybe I should clarify that the guy did not inform his fellow geocachers that they should wear scuba gear if they ventured into the tunnel.

  3. #3 Birger Johansson
    June 22, 2011

    Why did he not drill a hole to vent the noxious gas? Problem solved (yes, I understand the municipality might be less than happy about such alterations, but if he was serious about choosing that tunnel over alternatives I don’t see that stopping him). I thought anyone who have heard about exhaust and carbon monoxide would know that sealed cavities are bad for your health. Don’t get me started on anoxic caves.
    BTW do you have to do lots of GPS calibration before setting out?

  4. #4 Martin R
    June 22, 2011

    The GPS unit usually finds its place almost instantly unless I move far between turning it off and turning it on again. I do often however have to calibrate the compass. This is only necessary if you want the arrow on the display to point towards your goal, though.

    Other GPS units determine the direction of this arrow less exactly by assuming that your nose points the same way as your GPS unit and then looking at the latest two positions measured.

  5. #5 Nomen Nescio
    June 22, 2011

    any enclosed, unventilated space can turn anoxic depending on what’s in it and how enclosed it really is. hydrogen sulfide would make the hypoxia hazard far, far worse, but even without that, such tunnels are quite dangerous enough.

    unless the cache was literally taped to the underside of that hatch, it was by definition unsafe. the lock configuration might have perhaps been made safe, if the conventional padlock had been left in place, using a chain-of-locks approach (provided they could undo it without wrecking it); but there would have been no point, since entering the tunnel would still have been too hazardous.

  6. #6 Supporting the cache
    June 23, 2011

    I live in the village where this cache is placed. The tunnel HAS, I repeat, HAS ventilation. Next to the forest hatch there is a ventilation duct where air easily can pass in and out unrestrictedly. I myself have entered and walked the entire tunnel and logged the cache, and I would LOVE some evidence showing that there in fact IS poisonos gas down there, because if there is, why in the world would Mark Municipality not check on the both hatches frequently? I have a relative living near the forest where the unlocked hatch is placed that can confirm that this hatch have been cracked open for several years.

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