Almost all residents belong to the Roman Catholic, Evangelical Protestant, or Seventh-day Adventist churches, which in turn retain close ties with churches in Portugal. There is a small but growing Muslim population.
The Contador River is located in the northwest of São Tomé and its river valley is possibly the deepest in the country. Several streams run down from the volcanic highlands into the Gulf of Guinea.There are no significant lakes on São Tomé and Príncipe.
According to the 2010 revison of the World Population Prospects the total population was 165,000 in 2010, compared to only 60,000 in 1950. The proportion of children below the age of 15 in 2010 was 40.3%, 55.8% was between 15 and 65 years of age, while 3.9% was 65 years or older.