With its rugged mountains and awesome views, Hong Kong is a great hiking city. But what happens if you get lost between two peaks?
Two clever technical officers from the Scout Association have the solution - a GPS device that "pings" hikers' locations to other ramblers.
Henry Tsang Hon-wai and Alex Chung invented the device in 2012 as a way to track other hikers during competitions.
"Our prototype was first put on trial for the Island Scout trail, a charity walk from Big Wave Bay in Shek O to the Peak, in 2012," says Tsang.
"We bought some GPS devices from the mainland, which were made to track the progress of trucks delivering goods. A lot of work had to be done to adjust them to track hikers."
Like mobile phones, the GPS devices used SIM cards. During the trial, Tsang enlisted a 10-man team to text the device every 30 minutes to get its location.
"It was really clumsy, considering the hike lasts up to 12 hours and we had to have a room filled with people texting for hours non-stop to collect data. But it worked. We were able to get the location of hikers and plot them on GoogleMaps," he says.
Tsang knew there were still two hurdles: improving battery life and finding a better way to collect data.
The first step was to abandon the SIM cards. "We found that in most of Hong Kong, even in the mountains, internet connection is available, so we decided transfer data online and abandon the SIM cards. Then we tweaked the system to allow the GPS device to send data over the internet," he says.
Earlier this month, Tsang and Chung's hard work was finally put to the test, at the 17th Island Scout trail, co-organised by the Scout Association and the Rotary Club.
"The trail from Shek O to the Peak is 50 kilometres long, and goes through valleys where internet reception is unstable. So at medical stations - to ensure the tracking was accurate - we used QR codes for hikers to verify their locations on their phones," says Tsang.
He hopes the device will make hiking safer, and alert teams if they take a wrong turn.
"Luckily this year's event was smooth, with nobody needing the medics," says Tsang. "But if anything does happen, the teams will be told quickly and we'd know which check-point they are closest to."