Beads of sweat dropped to the ground. Students lay on the floor, panting, heaving. A shaking arm reached out for an almost empty bottle, desperate for a few sips of water.
No, this wasn't the finish line of a marathon or the changing room after an inter-school basketball match.
This was South Island School's Power Down Day, which took place on June 24.
That day, South Island turned off all electrical devices and appliances, including phones, lights, and air-conditioning units. But it was about more than just electricity or carbon emissions. The school came together as a community to live up to their motto - "MaD", or "Making a Difference".
And live up to it they did - the school saved more than HK$35,000 over the course of the school day (8am-3.10pm), all of which will go to Nepal relief efforts.
The day was jointly organised by the school's MaD Council and the MaD Council of Bahay, one of South Island's six houses.
Tarun Srivastava, a MaD council member who helped bring the event to life, explained the modest beginnings of Power Down Day. "Originally, we had planned on doing an Earth Hour event. But we felt that it would be just for show, and we needed a way to make a profound dent in our carbon footprint; a way to make students realise the extent of our energy consumption. That's when we thought of Power Down Day."
As anyone living in today's tech-dominated world can imagine, it wasn't easy being without electricity for seven hours. This was part of the inspiration behind Power Down Day, as Tarun explains: "We wanted to simulate the sort of problems we would have if we continue squandering electricity."
Simulate they did, with Nikhil Rekhani, a Year 10 student at South Island, seeing it as a competition to get through the day. "It was incredibly difficult - especially considering the air-con switch was right there, but we weren't allowed to use it. I got so sweaty I had to change shirts, so I thought to myself, 'Now the real game begins'. It was much more enjoyable after that."
The teachers took to it quite enthusiastically, too, with the school's principal, Graham Silverthorne, walking all the way from his home in the Mid-Levels to the school's secluded campus on Nam Fung Road in the morning and back after school.
However, he was careful not to feel too proud. "I was feeling like an adventurer - trotting down the steps towards the school. All of a sudden, I walked face first into a massive spider web! I've heard a lot of stories about people who find things in their ears - I've heard about a man finding a cockroach in his ear. So my first thought was to shield myself from the owner of this particular web. That definitely brought me down a bit," he said.
But it wasn't just a one-off experience. Shreyashi Saha, another MaD Council member, noted the possibility for expansion, saying, "I believe this is the beginning of a major awareness campaign in SIS. Our next step is to make sure we remember what we learned from this initiative."
She also had a warning for students who want to try to replicate the event. "I'd strongly advise having it planned really early. And you need to publicise it properly, so that the student body understands the importance and the purpose of the initiative."
South Island's Power Down Day wasn't just a feel-good, token ceremony - apart from saving thousands of dollars, they saved more than 5,000 kWh of electricity. On top of this, they avoided releasing more than three tonnes of carbon dioxide into the atmosphere.
Not only did they truly make a difference, they've also set a precedent for any schools who want to follow in their environmentally-friendly footsteps.