Filmed by Zhou Shengjie and Ma Xuefeng. Edited by Ma Xuefeng. Tranlsated by Xiang Ying. Polished by Andy Boreham.

It’s a lonely job working in the East China Sea, some 30 kilometers offshore from Shanghai. But a crew of lighthouse keepers on a tiny island fills a crucial role in maritime navigation.

Their base is 0.09-square-kilometer Dajishan Island. Four keepers rotate shifts over two or four-week stints. Chi Caiming, 51, is the crew leader.

Chi, who became a lighthouse keeper in 1988, spent 210 days on the island last year. On January 25, he began a shift that will extend through the Chinese New Year holiday, which starts on Monday.