2. Ontong Java Atoll, Solomon Islands

Occupying an area of 19.42 square kilometers, Ontong Java Atoll is one of the world's largest atolls. Most parts of this beautiful island are less than 0.18 meters above the sea level. The residents on the atoll live on fishing for more than 2,000 years. The rising temperature and growing acidity of the seawater are killing the earthly paradise, which also threatens the existence of locals.

Ontong Java Atoll, Solomon Islands [huanqiu.com]