Geocaching nears the million mark

You might have seen them. Normal-looking folk rooting through bushes, frisking statues and heaving up loose paving stones.

They stare intently. They bear rucksacks. And occasionally they smile - but only upon finding a grubby container. Welcome to the weird and wonderful world of geocaching.

This is the 2.0 version of a treasure hunt. Instead of metal detectors or mildewed maps, geocaching has GPS tracking; instead of Indiana Jones and treasure troves, it's Joe Bloggs and tiny trinkets. And rather than one big chest on a desert island, there are numerous 'caches' - tiny waterproof repositories - dotted around the globe.

A million caches
There were 700,000 caches listed at Geocaching.com in January 2009; 11 months later, there are nearly a million. And it all only started back in 2000. The recent arrival of multiple mobile applications further affirms geocaching's burgeoning popularity.

They also make it much cheaper. Where a decent GPS device is priced easily upwards of £50, mobile applications are far less. The official one by Groundspeak, Geocaching.com's founders, costs £5.99 for iPhone users, with economical alternatives are also available for owners of Windows phones and other handsets.

Keen to see what all the fuss was about, I chose Groundspeak's app and hired my equally curious chum Rob as an assistant sleuth. Following the application's instruction, I log onto Geocaching.com and register a free profile. After entering my postcode, I learn the rough locations of nearby caches.

Thanks to the proliferation of these caches, one is never too distant - especially in London. Mere minutes into our first foray - on a sleepy Sunday dotted with cagouled dog-walkers and still-carousing clubbers - and we're in business.

Treasure tracking
My phone has directed us off the busy Kings Cross Road to the paved area of a quiet square, hinting that we furtively check the four benches. I inspect the first, then the second, then the thir- joy! A dark tube is magnetically attached to the back.

Despite the giddy euphoria surrounding our find, Rob and I make sure to do everything by the geocaching book, like the professionals we surely are. While my cohort looks out for nosy mugglers, as 'cachers delightfully refer to the public, I open the case.

The contents are as forums led me to anticipate: a tiny but long roll of notepaper, on which I enter my profile name, and a gift (toy ladybirds), which I pocket and replace with one of my own (an FHM playing card). If you take a knick-knack, etiquette stipulates that you must trade it for something of equal or greater value.

I also remember to update the website, proudly confirming that we've found the goods, and then restore the cache to its home. We move onto our next selection, apparently outside a place called St Etheldreda's.

GPS-powered sightseeing
This turns out to be a ancient chapel, crammed into a narrow cul-de-sac behind Hatton Garden's jewellers. Cache located and the door open, we drift inside. With the songs of the parish service sounding distantly above, I find a musty, cobwebbed crypt. It's open to anyone who cares to poke around.

This underlines a truth constantly realised during the day: that geocaching is culturally beneficial. Many caches are stowed in fascinating, easy-to-miss locations, with online logs providing extra info. I discover that St Etheldreda's has London's largest stained-glass windows and is England's oldest Catholic church.

Handily, all caches are graded in terms of the difficulty involved in pinpointing them. That said, anything's tough for we amateurs. At the west gate of Queen Square, metres from Great Ormond Street Hospital, Rob and I simply cannot find our prize.

We've check noticeboards and trees with increasingly hot tempers. I pore over recent successful logs for clues. My accomplice repeats the annoyingly ambiguous hint over and over. Still nothing. Then, with almost every toy having been thrown from the pram, a rummage under a railing yields gold. It's easily the day's most satisfying find.

This satisfaction arises partly from personal achievement and the solving of a puzzle, but also via the feeling of having entered a shrouded new world. Despite taking place in public places, geocaching is wonderfully stealthy and secretive.

Strolling through Bloomsbury to our next booty, I suddenly find myself noticing new things on a route I've covered many times before. An old wall poster here; some street art there. It seems that geocaching makes me more alert, opening my dullard eyes to the many sights around.

A easily-snaffled cache close to Russell Square proves to be our last. Mobile phones might make geocaching cheaper, but they sure don't make it lengthier. My iPhone's famously feeble battery halts our fun. A resourceful and fast-trotting hunter with a more durable handset could expect to find 12 caches in a day in a populous area.

If you use the Groundspeak application, a lack of mobile power is not the only hindrance. Though the three map options are great - Microsoft Visual Earth being the best - a direction arrow suggests I walk through walls and a compass only tracks my turns with ponderous sloth. In a familiar city, I'm fine; areas further afield would be tougher.

All in good time, though. For now, Rob sensibly suggests we find a pub and review our day's toil. Next up for us might be the London monopoly trail; equally, we may create our own caches. Either way, we're hooked now - and we're certainly not the only ones.