Christmas in 2004, a 9.1 magnitude earthquake triggered tsunami waves that killed some 230,000 people across a dozen countries.

People started gathering in prayer today and visiting mass graves in Aceh, one of the worst-hit areas by the Boxing Day Indian Ocean tsunami which killed an estimated 230,000 people across a dozen countries.

Survivors and mourners gathered at mass graves in Indonesia, Thailand and other places along the Indian Ocean that were devastated by the 2004 tsunami — the deadliest in the world.