To get started, you first need to create an account via the geocaching website at geocaching.com. Next, you select the geocache you want to find, and are then given a set of GPS coordinates that you use to navigate your way to the cache using your smartphone or GPS receiver.

The very first cache was hidden on May 3, 2000 – a day after the United States government removed a feature known as selective availability from GPS systems that added intentional, time varying errors of up to 100 metres to publicly available navigation signals. This feature was used to deny an enemy the use of civilian GPS receivers. The removal of it allowed the public to receive accurate coordinates for their targets for the first time, and thus geocaching was born.

Hong Kong had its first cache placed on October 21, 2001.

You won’t find gold, diamonds or rubies in a cache. Instead you will most likely find a waterproof container with a piece of paper inside along with tradeable trinkets or knick-knacks, which all act as clues to the location of another cache or clue, or a travel bug – instructions to take the cache to another place in the city or even to another country.

Participants say the activity gets them outside to places they have only previously seen on Google Street View.

“You get to see so much of Hong Kong. My wife’s Chinese and I’ve seen more of Hong Kong than she has,” Tim Teahan, a local school teacher and avid geocacher, says.

“Geocaching has taken me to exotic locations. Before I started geocaching I wasn’t much of a hiker. I go hiking quite a lot now since I started geocaching.”

During a geocaching search at Cornwall Street Park in Kowloon Tong, the GPS coordinates and clues left by another player lead Teahan, and fellow geocachers Geoff Scollick and Sophia Wong, to a small pond. After some careful searching, Tim removes a magnetically attached “no climbing” sign to reveal a small plastic bag with a tiny log book inside.

Scollick marks down his user name and the date in the log book, puts it back in the plastic bag and reattaches the “no climbing” sign in exactly the same place he found it. The find is then logged through the app or on the website.

Even while on holiday, one of the first things dedicated geocachers do once they settle into a hotel is see what caches are nearby.

On a trip to Taiwan, Teahan made two finds near Taipei 101, the island’s tallest building.

“We go to the United Kingdom once a year and we go to lost pubs, we go to churches, different places of history,” Scollick says.

There are five levels of difficulty for a cache search. The levels are determined by whether an overnight stay is required, the distance from the nearest public transport station or car park, the amount of overgrowth that must be navigated through, the terrain elevation and the level of difficulty finding the cache once you’ve arrived at the coordinates.

Some caches require ladders, climbing equipment and even scuba diving gear. It all depends on how adventurous you are.

“In Shing Mun Valley … you go in through army trenches and you’re popping your head out and checking the GPS – because it doesn’t work in the trench – you use torches to go through and find the geocache,” Teahan says.

There are times when a cache is no longer there due to a cleaner having assumed it to be rubbish and taking it away, or non-players – known as “muggles” – checking what a geocacher found and taking it or just simply tossing it.

For anyone looking for serious adventure, there are even caches in Antarctica and space. Safe to say the difficulty level for those is a five.

What’s it called: geocaching

Who can do it: open to all

How much does it cost: free

How many people are doing it in Hong Kong: 1,000+

Where: caches are found all over the world

Where can I learn more: www.geocaching.com

Who’s doing it in Hong Kong: Geocaching Hong Kong www.facebook.com/groups/geocachinghongkong

What equipment do I need: smartphone or GPS receiver