The Amazon rainforest is one of the best places on Earth for ecology - studying the relationship between the environment and living things.
More than 2,000 different types of birds, mammals and amphibians call the Amazon home, as well as 2.5 million different types of insect.
At the end of July, the Yan Oi Tong Green Adventure programme teamed up with the School of Biological Sciences at the University of Hong Kong to offer students a chance to explore and learn about the Amazon.
The programme took 25 Hongkongers, aged 15 to 18, to Ecuador. They hiked through Cuyabeno and Yasuni national parks and saw the beauty of the Amazon.
But this trip wasn't just a holiday. "The trip was for learning and not for fun," explains Maggie Li Man-ling, 16, from Tsuen Wan Government Secondary School. "We had direct interaction with the rainforest during the trip, and saw lots of animals."
With boat trips along rivers and night walks through the forest, the students were able to observe the different species in their natural habitats. For students like Wilbert Li Wai-hang, also 16 and a student at Diocesans Boys' School, seeing the animals in their natural environment was what the trip was all about. "I'm really interested in animals, particularly amphibians or reptiles," he says. "Usually you can only see them in the zoo or on TV."
The students focused on different topics before the trip to help them prepare for what they would see in the rainforest.
Maggie's group researched reptiles, mammals and amphibians. "We had a target list of what we would like to see in the rainforest," she says.
Maggie and her group also found a surprising connection between Hong Kong and the rainforest. "There's actually some poison dart frogs from the Amazon that are being sold in Hong Kong markets," Maggie explains. These animals are taken illegally from the rainforest and often sold as pets in Hong Kong.
Crystal Cheung Lok-ching, also 16, from Cheltenham Ladies College (UK), says she thinks that a lot of people in Hong Kong don't know where these animals come from. "People like having exotic pets like parrots, but they don't realise these animals are illegally hunted or illegally taken from places like the Amazon," she says.
What's more, people who buy exotic pets often don't understand how to properly care for them.
"I remember one of our guides [in the Amazon] told us that the ones who kill the animals are not the people who sell them, but the ones who buy them," Maggie says. "So we need to tell Hong Kong people that it's not impossible to save the animals. It can just come down to not buying them."
Looking after the Amazon is important, but the students believe that the lessons they learned from the rainforest can help locally, too.
"In Hong Kong now, a lot of people know our environment is facing serious problems, and they know they should do something," says Toby Tsang Pak-nok, a 23-year-old HKU student who helped as a tutor on the trip. "But it's hard to change people's behaviour, and many aren't motivated to change. First, people need to feel more connected to nature."
Toby thinks that connecting with nature will help Hong Kong people care more about ecology, both at home and in places like the Amazon.
The trip certainly made an impact on the students. Maggie says she was studying biology before, but she is now considering focusing on ecology. "People always say that studying finance or economics can earn you more money in the future," she explains. "But now I think that doing something more meaningful is much more important than just earning money."