[Photo provided to China Daily]

The first one was in 2014.

"This (the limited edition) is not only for more sales. Of course, we have to sell. But we want to give back to the Earth," says Alain Delamuraz, vice-president of Blancpain.

"People can buy different watches, but when they buy a Blancpain watch, they contribute to a commitment that they agree with," he says.

Founded in 1735, the brand has been closely related with diving since its launch of the Fifty Fathoms, the first modern diving watch in the world, in 1953.

The brand initiated the Blancpain Ocean Commitment project in 2014, and has so far supported 10 expeditions and the protection of 3 million square kilometers of ocean.

It has also sponsored scientific projects, underwater photographers, environmental forums and exhibitions, in order to raise public awareness.

Meanwhile, Laurent Ballesta, a marine biologist and research diver, shared his underwater experiences and findings from a scientific expedition to the South Pole, which is supported by Blancpain, at the Shanghai event.

"We are very lucky to be on this planet where there is much more water than land. There is Google Earth but no Google Ocean. You really have to go into the water to see what is down there," says Ballesta.