In the low-lying islands of the Maldives, high waves and floods have caused chaos. Some of the 200 islands cannot be contacted.
Some BBC News website readers sent emails about their experiences of the disaster.
For three hours on 26th December, 50 per cent of the population was swimming in water. Maldives is still miraculously lucky to survive with few casualties. The strength is still there; instead of weeping you find men and women, the youth, nationwide working hard for relief. The scene now is as terrific as it was horrific before.
Anzala Fahsha, Male
We were both in the Maldives on Hakurra Club Island when the tidal wave hit. Water bungalows were washed away, the whole island was covered by water, we had nowhere to run, the water just kept coming towards you. We are home now, safe.
Tony and Amanda Howells, Lincoln, England
I was working at a resort in the Maldives. At 11.00 the sea started to rise and suddenly guests and staff were fighting for our lives: the waves got so high some were nearly washed out to sea. All of our rooms were destroyed. To our horror the wave came back again, from the opposite direction, and smashed us again. All power and water are gone and all staff have been evacuated. But some resorts within sight are not affected.
Patrick, South Ari atoll, Maldives
The death toll is likely to rise. Dhaalu Atoll is very badly hit. Most tourist resorts are being evacuated to the airport island and some tourists taking refuge in schools on Male island. Those who own large vessels have been urged to travel to populated islands and fishing areas to help rescue people. The only radio station is just broadcasting prayers and no news. There is panic in some of the islands due to lack of news from elsewhere in the country.
Haifa, Villingilli, Maldives
Male is protected by a special artificial barrier and yet it has been flooded and destroyed. The other islands have no protection - there are thousands of these islands with thousands of people on them, including tourists, and there's no form of communication to even let them know what is happening. Very sadly, we fear there may be thousands dead, including fishermen and divers.
Ali, Male, Maldives
We are badly affected. Numbers of low-lying islands are almost submerged. The local people are seeking refuge in small dhonis. Most of the islands are out of electricity, food and water and the sewage system is totally destroyed. The government is totally unable to send help to these small islands. Many islanders have to spend the night outside since so many houses have been destroyed.
Ayya, Male, Maldives